Bug: Terrain options duplicated do not show original in Set Terrain drop down

[Trahloc]

I have 4 terrains:
Example (filled with all your defaults so I can reference it)
Difficult Terrain 1/2 (Multiply 0.50)
Difficult Terrain 1/3 (Multiply 0.33) <-- not shown
Difficult Terrain 1/4 (Multiply 0.25) <-- duplicate of 1/3

Difficult 1/3 does not show up in the drop down. 1/4 is a duplicate of 1/3 and it shows. If I delete 1/4 then 1/3 will appear.

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I'm using Foundry v12.331 with 5e and Terrain Mapper version is 0.4.9.