[Twixi]

I want to import a new song in MSP for which I have different versions. I have choosen a filename convention for jpg files like this:
My new song (V1).jpg
My new song (V2).jpg
After the import MSP confirms both files successfully imported. But checking the songlist shows only song "My new song (V1)" is present in MSP. Checking file details for song "My new song (V1)" shows that both files imported above belong to the same song.

Repeating the same steps but now with pdf files
My new song (V1).pdf
My new song (V2).pdf
results in two different songs in MSP. This is what I want.

For jpg files, is this expected behaviour? Can this feature be switched off?
MSP version is 2.5.9.

Thanks