Double entry checker

Hello All
Namaste from Nepal

Is it feasible in ODK to display a message like "this number is already entered" if the unique ID "1010" is inputted again into the designated field?

Thank you in Advance

Is this inside of one submission? Or, are you looking to do this across multiple submissions?

Also, is this for a single device? Or, is this across multiple devices with different data collectors?

This documentation on a worflow for encounters with known entities may be helpful: