Do you mean mixing both in the same bowl? I do this with my cats some times. No, it is not very beneficial but mine like it and it's one of my ways to get them to eat any canned food other than the pate varieties! :lol3:
There's nothing wrong with feeding wet at some meals and dry at others.
We do the same also. Mornings they get wet but being as we're on a tight schedule to get out of the house, if they don't finish (sometimes our older boy will only eat 1/2 his portion) I'll pull up the bowls and replace them with some kibble.
At night it's wet but they almost always get a little more kibble overnight to tide them over. I do make sure the quality of kibble is the best available: high protein and with a minimum of fillers.