Dedicated server sees duplicate mods

[naqaden]

...when BetterPortals is the only mod present. The first line reveals it is looking at an extra relative path to the same jar. No such issue in single player.

Tested on MinecraftForge v14.23.5.2836

[Server thread/FATAL] [FML]: Found a duplicate mod betterportals at [G:\minecraft\1.12.2\.\mods\betterportals-0.1.0.jar, .\mods\betterportals-0.1.0.jar]
[Server thread/ERROR] [minecraft/MinecraftServer]: Encountered an unexpected exception
net.minecraftforge.fml.common.DuplicateModsFoundException:
Duplicate Mods:
        betterportals : G:\minecraft\1.12.2\.\mods\betterportals-0.1.0.jar
        betterportals : G:\minecraft\1.12.2\.\mods\betterportals-0.1.0.jar
        

        at net.minecraftforge.fml.common.Loader.identifyDuplicates(Loader.java:464) ~[Loader.class:?]
        at net.minecraftforge.fml.common.Loader.identifyMods(Loader.java:426) ~[Loader.class:?]
        at net.minecraftforge.fml.common.Loader.loadMods(Loader.java:566) ~[Loader.class:?]
        at net.minecraftforge.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:98) ~[FMLServerHandler.class:?]
        at net.minecraftforge.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:333) ~[FMLCommonHandler.class:?]
        at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:125) ~[nz.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:486) [MinecraftServer.class:?]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_211]