Yes you can shoot pearl over metalics, but may I ask why you want blue pearl over a blue metalic?
I highly suggest you spray a test panel to see the effect it will make.

Are you trying for a certain look? like changing colors at different angles ?
Like a floping paint job?

If you can try and clue me in on the look you want I will try and help you on it .

As I use the PPG powdered pearls everyday when I mix color.
I just spot painted 2 tri stage pearl front ends today , but they were the pearl coat first and tinted clear second, like a candy. Is this the look you are wanting like the bright reds on the new cadillacs?

SprayTEch