If you have a quarter with both sides tails and you looked at it magnified and there seems to be no trace of two coins being joined together is it real?

Possibly. You could check with the US Mint to see if there were any coins minted with that defect.

Answer

The mint won't help. You need to contact one of the major grading/certification services like ANACS or PCGS. Check a recent copy of any of the coin collecting magazines to see if there is a major show in your area. If you are near Kansas City, the ANA convention is coming up on April 9-10 and all the certification services will have booths. They will give a free opinion, but if you want to have it certified, you'll have to submit it with the required fees.

Final Answer

It's not a defect and the grading agencies will almost certainly tell you that you have what's called a magician's coin. There's more information at the Related Question.