Help tracking leads from events

Hi all!

My company recently sponsored two events at two different locations over the weekend. To assist with lead capture at the events, my team built two landing pages with unique forms to track the succcess of each page. However, at the events only one landing page was used. Now my team is trying determine how we can identify which leads came from which events. There was not a postal/zip code field on the form, so it has become more difficult to do this. I wanted to tap into the community to see what suggestions you might have to differentiate which events people attended?

Thanks in advance!

-Megan