Issues with clipping mask

Hello!

I'm creating a digital scratch card in illustrator for a client, but have run into a problem.

The scraper part consists of two separate files (a background and a file with the actual surface to be scraped)

This is how the files are made and exported;

Background = Jpg

Surface with scraping = clipping mask and exported as png

These two files should be able to be placed on top of each other so that they merge with each other.

However, it seems that the clipping mask I create adds or subtracts a pixel because there is a clear line between the two files...(please see attached screenshot) 

I feel like I've done everything to get around this problem so would really appreciate it if someone could help me. Thanks in advance!