Sorry, but that is not possible. Whilst you can remotely access different accounts on other machines, either over your home network or further afield, (providing that you have the correct permissions and credentials), you cannot use remote access from your machine to access A/C 2 whilst you are currently running A/C 1 on the same machine.
Is there any reason why you want to do this? If, as you say, it is the same machine, why don't you explicitly log in to the account in question and access it that way?