You can have more than one doctor at once, there was the 5 doctors episodes and the 3 doctors episodes.
Ah but on those the timelords frigged it so that they could all come together at once....the three docs were at Omeg's tomb where things don't work like in the real world, the recent two docs were in a tardis, the five docs were brought throught he matrix IIRC (no, not that matrix, the galafray one), and the two docs with the spud 'eds...well that was Jim Davidson when they didn't care about the integrity of the universe if it meant getting a few more viewers. No timelords or matrix now* so it'd be a bit tricky. Anyhow, if she were he then she'd have know what the solution was from the start and there'd have been a lot less faffing.
* well, yes, "now" is relitive to a timelord....but that leads on to the whole bag o'fish about why thetimelords were wied out if they knew what was going to happen in the future.....a slight problem that I don't think the script writers will want to tackle.
As for the Dr's name...I think that Steven Moffat is probably one of the few fans of the later Sly McCoy episodes...Silver Nemisis dropped a bit of a vague hint.
