I cannot think of a reason for germinating more than one seed variety in the same bag. Or for dividing the same seeds into different papers. Mold, if that is what you are seeing is to be avoided if possible, if not try some peroxide because if you don't kill the mold it will kill the seeds. Al

The pink mold is usually not good but maybe only some of the seeds in the batch are rotten. So remove those, keep those that are firm if any, soak them in water with some peroxide and then put them in a new paper. This year I dipped the infected seeds in alcohol and then let them airdry before wrapping them up again. That has worked so far too.
Some seeds do stain the paper when they start off though.

I've done a couple of different varieties of seeds together. After a while you can have so many baggies taking up the same space and you realize you can condense some. Once they sprout I just remove them into the pot they were suppose to go into.

The only problem I've run into is bagging the same variety but different names. Trying to figure out which were which is a PIA. Much easier to do seeds that look dramatically different in the same baggie.

I've been writing a recognizable abbr. of the name on a small piece of plastic with indelible marker and placing it with the seeds.

I'm hoping to save on jiffy pots by placing only germinated seeds in them.

Any other tips 'n' tricks welcome here!

Some of my towels have gotte pink mold, but it does not seem to affect the seeds much, that I can see. I keep my seeds in separate baggies. It's just easier to keep track of who's who.