There is a really nice duplicate prevention capability in Vtiger 7 (as seen in Vtiger On Demand). The nicest aspect is that you can set the duplicate check criteria (up to 3 fields) and the system will proactively check dupes as contacts are created across many different areas in vtiger including:
- Full form – create contact
- Quick create form – create contact
- Web form – create contact
It’s worth noting that imports do not have use this dupe check as there is a separate dupe check built into imports.
https://helpdocs.vtiger.com/app/home?articleid=877