FilterRename doesn't merge same names

[arrowmaster]

NamesAndIcons.cfg has some renaming setup for RealismOverhaul that is outdated. While attempting to update these I noticed that FilterRename doesn't seem to merge subcategories with the same name. For example there are multiple propellant types for SRBs in RealismOverhaul that the current config is renaming to SRBs. In game only the ones using PBAN appear in the SRBs subcategory while all others disappear from the FE Engines category and can only be found under Filter by Function.

FilterExtension/GameData/000_FilterExtensions_Configs/Default/NamesAndIcons.cfg

Lines 3 to 29 in b115635

	name = Aniline,Furfuryl,IRFNA-III=>Sounding Rockets
	name = Ethanol75,LqdOxygen=>Early Rockets
	name = Ethanol75,HTP,LqdOxygen=>Early Rockets
	name = Ethanol90,HTP,LqdOxygen=>Early Rockets
	name = Hydyne,HTP,LqdOxygen=>Early Rockets
	name = AK20,Kerosene=>Early Rockets
	name = Kerosene,LqdOxygen=>Rockets
	name = LiquidFuel,Oxidizer=>Rockets
	name = HTP,Kerosene,LqdOxygen=>Rockets
	name = IWFNA,UDMH=>Upper Stage Engines
	name = HTP,Kerosene=>Upper Stage Engines
	name = IntakeAir,LiquidFuel=>Jets
	name = IntakeAir,Kerosene=>Jets
	name = IntakeAir,AvGas=>Jets
	name = SolidFuel=>SRBs
	name = HTPB=>SRBs
	name = PBAN=>SRBs
	name = PSPC=>SRBs
	name = NGNC=>SRBs
	name = HNIW=>SRBs
	name = MonoPropellant=>MonoProp
	name = HTP=>MonoProp
	name = Hydazine=>MonoProp
	name = Helium=>MonoProp
	name = Nitrogen=>MonoProp
	name = NitrousOxide=>MonoProp
	name = CaveaB=>MonoProp