Blue + Green Name Merging

[ajdes]

Sorry if this has been answered, I read through a bunch of posts and couldnt find it.

If I decide to reuse a blue character's name on green (which I can do because its the same account). What happens if/when the servers are eventually merged?

Will one character overwrite the other? Will I have the option to rename one? Will one character name just get some bogus random characters appended?

Basically what I'm getting at, is it a bad idea to reuse my blue names on green?