I received a payment about 18 hours ago, and it is still unconfirmed. The transaction log is here: https://blockchain.info/tx/b6deeee2d2bc1b015aa3d73346216cd90dbcd5bda3943771fc5377765ab15e25

I know the low fee might be a factor that causes the delay of the confirmation. But there is another thing that raised my concern: the red label which says "Double Spend!" How can "Double Spend!" affect a transaction? From the info I found on the internet, it is not a good sign.

P.S. I found a transaction acceleration service called ViaBTC and had submitted the unconfirmed transaction to it 15 minutes ago. But I think it is still necessary for me to figure out the effect of "Double Spend!" so I opened this thread.