Multiple Emails From 1 Person

Hey fellow Maketo peeps -

I was wondering if any of you have dealt with the following scenario:

• We have a person in Marketo, let's call him Dave Smoot. Dave works at Intel.
• We have him in our Marketo instance with email address dsmoot@intel.com.
• The Activity log indicates that mails are delivered successfully and he opens mails, clicks on links --  so the email address is valid and active.
• We then get his name from a tradeshow list that has a different email address tied to it: dave.smoot@intel.com (for argument's sake).
• Dave monitors this mail too and opens mails etc... So again it looks like a good and active email address.

My question to you all is this: how do you deal with multiple entries of good email addresses? We don't necessarily want to merge the 2 email addresses as they are both valid. But if there was a way for them to both be tied to the same person (so we don't double mail the guy, for example) that'd be super helpful. It doesn't look like Marketo has a nested feature (like account hierarchies in SFDC) but then again maybe I'm missing something.  Anyways, would love to hear your suggestions!

Thanks.