Could not get load ID. We're asking for something which was never added during LoadingVars. pathRelToParent=/sourcePrecept, parent=EndTable125766
UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Log.Error_Patch2 (string)
Verse.LoadIDsWantedBank:Take<RimWorld.Precept_ThingStyle> (string,Verse.IExposable)
Verse.CrossRefHandler:TakeResolvedRef<RimWorld.Precept_ThingStyle> (string,Verse.IExposable)
Verse.CrossRefHandler:TakeResolvedRef<RimWorld.Precept_ThingStyle> (string)
Verse.Scribe_References:Look<RimWorld.Precept_ThingStyle> (RimWorld.Precept_ThingStyle&,string,bool)
RimWorld.CompStyleable:PostExposeData ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.ThingWithComps.ExposeData_Patch1 (Verse.ThingWithComps)
Verse.Building:ExposeData ()
Verse.CrossRefHandler:ResolveAllCrossReferences ()
Verse.ScribeLoader:FinalizeLoading ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Game.LoadGame_Patch2 (Verse.Game)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.SavedGameLoaderNow.LoadGameFromSaveFileNow_Patch1 (string)
Verse.Root_Play/<>c:<Start>b__1_1 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c:<UpdateCurrentAsynchronousEvent>b__28_0 ()
System.Threading.ThreadHelper:ThreadStart_Context (object)
System.Threading.ExecutionContext:RunInternal (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object)
System.Threading.ThreadHelper:ThreadStart ()

The same with a dresser

I can second that:

Loading game from file BugTest with mods:
- Ludeon.RimWorld
- Ludeon.RimWorld.Royalty
- Ludeon.RimWorld.Ideology
- Ludeon.RimWorld.Biotech
- Ludeon.RimWorld.Anomaly
- Ludeon.RimWorld.Odyssey
- Rimsenal.Spacer
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Message (string)
Verse.SavedGameLoaderNow:LoadGameFromSaveFileNow (string)
Verse.Root_Play/<>c:<Start>b__1_1 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c:<UpdateCurrentAsynchronousEvent>b__28_0 ()
System.Threading.ThreadHelper:ThreadStart_Context (object)
System.Threading.ExecutionContext:RunInternal (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object)
System.Threading.ThreadHelper:ThreadStart ()

Tried to register the same load ID twice: null, pathRelToParent=/sourcePrecept, parent=Apparel_ArmorHelmetMechCommander43531
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Error (string)
Verse.LoadIDsWantedBank:RegisterLoadIDReadFromXml (string,System.Type,string,Verse.IExposable)
Verse.LoadIDsWantedBank:RegisterLoadIDReadFromXml (string,System.Type,string)
Verse.Scribe_References:Look<RimWorld.Precept_ThingStyle> (RimWorld.Precept_ThingStyle&,string,bool)
RimWorld.CompStyleable:PostExposeData ()
Verse.ThingWithComps:ExposeData ()
RimWorld.Apparel:ExposeData ()
Verse.ScribeExtractor:SaveableFromNode<Verse.Thing> (System.Xml.XmlNode,object[])
Verse.Scribe_Collections:Look<Verse.Thing> (System.Collections.Generic.List`1<Verse.Thing>&,bool,string,Verse.LookMode,object[])
Verse.Scribe_Collections:Look<Verse.Thing> (System.Collections.Generic.List`1<Verse.Thing>&,string,bool,Verse.LookMode,object[])
Verse.Scribe_Collections:Look<Verse.Thing> (System.Collections.Generic.List`1<Verse.Thing>&,string,Verse.LookMode,object[])
Verse.Map:ExposeData ()
Verse.ScribeExtractor:SaveableFromNode<Verse.Map> (System.Xml.XmlNode,object[])
Verse.Scribe_Collections:Look<Verse.Map> (System.Collections.Generic.List`1<Verse.Map>&,bool,string,Verse.LookMode,object[])
Verse.Scribe_Collections:Look<Verse.Map> (System.Collections.Generic.List`1<Verse.Map>&,string,bool,Verse.LookMode,object[])
Verse.Scribe_Collections:Look<Verse.Map> (System.Collections.Generic.List`1<Verse.Map>&,string,Verse.LookMode,object[])
Verse.Game:LoadGame ()
Verse.SavedGameLoaderNow:LoadGameFromSaveFileNow (string)
Verse.Root_Play/<>c:<Start>b__1_1 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c:<UpdateCurrentAsynchronousEvent>b__28_0 ()
System.Threading.ThreadHelper:ThreadStart_Context (object)
System.Threading.ExecutionContext:RunInternal (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object)
System.Threading.ThreadHelper:ThreadStart ()

I can also 100% force this bug:

As shown aboive:Rimworld clean + Rimsenal Faction Pack - Spacer loaded ingame as mod. New colony started, put a dresser, end table and some of the mech commander helms on the map. Save, direct reload - you will see the error messages in the console. I have no problems with any other mod.

It will shown up after some time playing too, forcing strange "Tried to register the same load ID twice" and other errors related to deep saving for dresser and end tables... don't ask me why, but it is consistent.

I get the feeling it is a false positive from 1.6 triggered by something this mod is doing because the items are loaded and saved fine - just start to spam that message.