I'd say it's perfectly acceptable. I'm walking the path of Kemeticism, but I work with Norse deities on the side. So why can't you do the opposite?
My suggestion is only that if you build altars/spaces for them both, you separate them some. Some of the things that the Norse deities like as offerings, Kemetic deities won't necessarily like. For instance, blood. Odin might enjoy a blood offering, while Min spazzes out about it.
I'd also suggest that you learn about the deity you want to work with (and their culture), before you begin working with them. For instance in the above, Odin might be okay with possessing your body and working through it, whereas Min spazzes out that you don't have the right equipment. Min's equipment is a big part of his personality, so removing that or not having is bad. Whereas Odin might not care as much because it isn't a big part of his personality.
I hope that makes sense. :)