outlook / entourage and merge identities?

The forums at microsoft mac support seem to have disappeared. I realise the above software isn't apple but hoping someone here will know the answer.

A computer has the same mail account in entourage and outlook. However, entourage got taken offline a year and half or so ago. However, the identity was not deleted to maintain access to emails on the computer.

I am not sure why it wasnt done the first time of use. But:

Is it possible to import the entourage database into outlook without overwriting what is in the outlook box. Will it add / back fill emails to outlook?

thanks for any help