Andrew Kin Fun Chan shares his python script for baking V-Ray dirt maps for assets that have multiple tiled UVs set for them. The Multi-Tile VRay Dirt Baker creates a shader with the V-Ray dirt texture and assigns that to the selected geometry in the scene.
It will then render out the V-Ray Dirt Maps based on the minimum and maximum UV range values, and cleans up the names of the maps created, and updates the output render image to be UDIM Mari-friendly.
Multi-Tile VRay Dirt Baker is a python script so it works on all platforms running Maya. One small caveats for using the script is that the object you are baking needs to combined as one piece in Maya. It also need to be the only object in the scene.
The Multi-Tile VRay Dirt Baker actually bakes out a map for each object in the scene file, so if there are more objects than one in the scene, it will do those as well.
You can find out more about the Multi-Tile VRay Dirt Baker here.