Check/prevent duplicate model numbers

[lokksta]

Hi,

 

Can this be done?

 

I'm thinking of something like when you enter the model no. in admin, if you enter one that is already in the database, it returns an error or something like that?

 

I have searched the forum and saw a few posts about checking for duplicates using easy populate, but I don't really want to use that if possible.

 

Thanks.