Weird Mark on Negative

[chchk]

Hello
I just Process BW120 Film Ilford Xp5 For My friend and I just found unacceptable mark on Negative. It's look like Chemical Stain mark or something but it happen more on 1-3 Frame(A little bit on another frame). The mark are merged on emulsion like fungus on the lens but I guess not.
Any one please tell me How it's happen

 

[Kino]

Welcome to Photrio!

It appears to be a classic case of backing paper imprint. This most often happens when film is exposed and left in a hot, humid environment for an extended period of time - OR- the film was stored in a hot environment prior to shooting.

How long did your friend have the film before shooting?
Was the film expired before making the exposures?
Was it stored in a cool dry place?
How long was it in the camera before being processed?
Was the camera stored in a cool dry place?

Also, the image posting system on this board can be confusing; can you edit your original post and retain only one copy of the images?

Thanks!