I don't see why not.
You can take any amount of free actions in a round, limited only by DM's discretion.
Anything that takes more time than a free action but less than a move action is counted as a swift action (including an immediate action)
The substitution rule for taking two moves instead of one move and one standard was written before the introduction of swift actions.
I therefore suggest that the text limiting you to one swift action per round refers to the amount of time it takes to peform that action (as relative to free actions) and that it does not restrict you in substituting a move action for a swift action.
Of course, if someone can point me to a direct contradiction of that (other than the already mentioned text) I can be easily persuaded otherwise.
I don't think casting multiple spells in a round is considered a problem, since the Quicken Spell feat already allows two spells in a round.
Also, most swift spells are hardly powerfull, and most of the time only last one round (from which you must try to benefit using your remaining time....)