[MCL-11155] Version with two tweakClasses no longer works

When trying to use a profile with a custom version that passes two mod's --tweakClass parameters in the arguments section the launcher will be unable to start and show a "failed to start" error. This worked correctly with the previous iteration of the launcher. (And both of them actually did something)

Here is the version's json used:

{
  "id": "1.13.2-MB_Modpack_pre1",
  "inheritsFrom": "1.13.2",
  "time": "2019-04-2414:40:40+01:00",
  "releaseTime": "2019-04-24T14:40:40+01:00",
  "type": "release",
  "libraries": [
    {
      "name": "optifine:OptiFine:1.13.2_HD_U_E7"
    },
    {
      "name": "org.ow2.asm:asm-all:5.0.3"
    },
    {
      "name": "me.dags:daflight:5.3.0-mc1.13.2"
    },
    {
      "name": "net.minecraft:launchwrapper:1.12"
    }
  ],
  "mainClass": "net.minecraft.launchwrapper.Launch",
  "minimumLauncherVersion": "21",
  "arguments": {
    "game": [
      "--tweakClass",
      "optifine.OptiFineTweaker"
    ],
    "game": [
      "--tweakClass",
      "me.dags.daflight.launch.DaFlightTweaker"
    ]
  }
}

Is there a different way to use multiple tweak classes now? Because I couldn't find one... (apparently Optifine seems to run fine though without specifying their tweak class so it's working in this case I guess? Maybe the previous launcher just ignored the duplicate argument?)