Attaching Two Email Addresses to A Lead Record?

In general, I haven't seen a good solution to this. Poosibly you could attach the work email to the personal email contact as a custom field and have sales look at that, but in general it is pretty tricky.

Also, I suspect making the link between the two at scale would also be hard. There might be some specific cases where you can manually ID these guys but finding automatically would be tough.

I'm curious as well to hear what others say.

We frequently have leads use different email addresses in filling out forms and when replying to emails with the resulting creation of either an unknown Marketo lead record or a name duplicate record.  When either occurs, we send an alert email to the lead owner or the person that sent the sales email that created the unknown lead record.  Most of the time, we ae able to identify the cause as a different email address for the person and we add the non-work email address to a secondary email address on the lead record, so that it can be found via search in SFDC and we merge the two records together, so that all the activities are displayed on a single SFDC record.  It's a manual process, but not unmanageable. 

There is an Idea The ability to match a secondary email address to existing records, rather than creating a new record. with a  "We Like It, But It's Complicated" status that will help make this process a bit more automated, and you may want to vote for it.

Or you may have them include a URL to the other version of the lead