Hi Carot, and Welcome to WriteWords
Until you've signed with an agent - and unless you've agreed to a period of 'exculsivity' with the first agent while she looks at your ms - there's nothing to stop you from sending your ms to the second agent.
It is usually best to be honest with both agents and tell them that others are also interested.
At present the business is suffering from the recession and acquisition meetings are being cancelled, so it may mean an extra long wait, but it's good news that 2 agents are interested, so hopefully it should work out for the best in the end.
- NaomiM
<Added>oops, apologies, that should of course have been
'Hi Carrots...'