Duplicate Records Warning

We use leads to qualify prospective buyers. We have two sales tiers, online sales consultants (inside sales) and onsite sales consultants (outside sales). It can happen that a prospect fills out a registration form online which creates the lead, then also goes to a show gallery in person where the onsite sales rep might register them again thus creating a duplicate lead. We do have workflows that prevent duplicate lead creation but there is no warning to let the sales rep know they have tried to create a duplicate lead. This causes confusion since the sales rep will look for the lead they just created and will not know to look for the original lead. A warning message would solve this issue since it will notify the sales rep of the duplicate lead.