Hi,
I have written after insert trigger on contact object.
After creating a contact,  I am creating a lead.

I getting an error  "FATAL_ERROR System.DmlException: Insert failed. First exception on row 0; first error: DUPLICATES_DETECTED, You're creating a duplicate record. We recommend you use an existing record instead.:"

I am not getting this error while creating the same lead manual. 

Thanks In Advance