Are you housing those 2 BP's together? If so I would strongly recommend that you separate them.

Here's why:

1) Cannibalism, not common, but there are DOCUMENTED cases. This alone isn't worth the risk.
2) Stress. Even the most friendly snakes get stressed out, so why cause the stress? Snakes have no want or need to be with another snake unless it's for breeding purposes. Other than that, it's just an unwanted roommate that they can't get away from.
3) Space. They will constantly try to dominate eachother for the best spots in the enclosure, even if you have multiple hides, you'll mainly see them together in one spot. People usually see this as "cuddling". It's not cuddling, they are fighting over the best spot.
4) You wake up in the morning after feeding and there's a regurgitated mouse. Which one did it?
5) One gets sick, now both are sick. That's 2X the vet bills, 2X the medications, and 2X the stress.
6) You are told the new snake you bought is the same sex as the one you already have. a year later, you find eggs in the enclosure. You have not prepared, no incubator, no space for babies, and no one to sell them to. What do you do now? The pet store/vet/person sexed them wrong.
7) Quarantine. How are you going to quarantine the new snake away from your original one? As you gain more experience, you'll find that quarantine is a NECESSITY. You could get a perfectly healthy snake, or one covered in mite eggs that hatch 3 days after you bring it home. Now both snakes have mites. Snakes also can take a long time to start showing symptoms of illness, now you got your original snake sick because you didn't quarantine.

Those are just the more known and common issues with housing multiple reptiles. The list goes on. The only pro to housing them together is to save space in your house by only having one enclosure, but is it worth it? That is up to you. People that say "I house two together and they are fine", they are fine now but with them being housed together there is NO guarantee it will stay that way forever. The only way to avoid future issues is to house them separately.

As for the difference in color for sure the darker snake is about to go into shed (make sure that your humidity is at least 60%) Once the snake sheds you will be able to see his/her true colors after he/she sheds. There is a huge variance in how normals looks... just like there is a huge variance in the way people look. A snake is only considered a morph if the color/patters can be passed on genetically with predictable results.