Replacing a pc power supply- does it have to be exactly the same?

I need to replace the power supply on my PC. It is a 400 watt ATX. I can find 400 watt replacements, but the Amps are different (on the table on the side of the power supply). Example: +3.3V with 15.0 A below on the old one and + 3.3V with 30 A below on the new one. Does this matter? Or will this damage something?