I have a question:

You have 10 slots in which to put the numbers 1-5 and each number must be used twice but no more than twice. (ex: 5 5 4 4 3 3 2 2 1 1 ex. 5 4 5 3 2 4 1 2 1 3.) How many different combinations are there? ( I think i know the answer but i just want to double check)