This has been [discussed on MSO][1]. The accepted answer is as follows:

> Cross posting is fine, provided:

> 1.    You respect the differences in the audiences at the different sites;
> 2.     You allow some time to pass between successive questions, and update them in the light of the answers previously received; and
> 3.     Really the first point again, you should have an idea what the new site offers in terms of expertise to crack your question that the previous site did not.

>Usenet-style forum spamming is, I hardly need to say, bad.

So asking the same thing is fine, but exact copy-pasting may not be appropriate, you should at least try to tailor it to the site.

As far as migrating, If a question is on-topic on a site, it is not migrated even if it would be on-topic on another site.


  [1]: http://meta.stackexchange.com/q/65931/172958