Read error messages before posting question on forum. The answer is given in this error message, check element with this number in .dat file, maybe you have two elements with the same ID.
You can post .dat file here.
On an element definition card (i.e. CTETRA), Field 2 is the element ID number (EID):
"Non-unique field 2" means that there are two (or more) elements in the input deck that have the same ID number.