Hey guys

So, I booked a flight on Delta.com using my credit card last May 23rd for a flight from JFK-SAN which cost 600$ (comfort+), while booking there was no errors, and only clicked the pay button once. After paying it did hold funds from my credit limit and after a day the charge for the ticket posted on my account. Earlier today as I was checking my credit card account my limit wasn't right. Called up my credit card company to ask, they told me there was another charge which showed as floating which was charged May 24th for the same amount 600$ by Delta. My bank told me to call again since it was still on hold or floating and not posted on my account yet. I then called up Delta which they said under my name and my credit card used showed only my booking for 1 ticket JFK-SAN which was 600$. Delta advised me that it might be a glitch on their end and to see if the double charge really gets posted by the next business day which is this Monday. Anyone had this thing occur to them previously?

If it does get posted into my account, is it a good idea to communicate with my bank only or with delta too?