I travel quite a bit and in most countries I'm required to show my passport to get a sim card. However, in several countries I've bought at least 4 or 5 sim cards by now (non tourist sims I mean) so there doesn't seem to be a limit on how many numbers you can have, they just want each number to be linked to a real person.
Of course it may be different in some countries, but it's worth checking to be sure.
