What could be causing this?

Question

MySQL

I make a request to a page from a browser. everything works out, BUT with a random probability this happens:


i.e. after 3 seconds, it cancels, accesses the same address only via http, gets 302 and makes a request via https getting 200.

Bottom line:
1) The request is slow.
2) 2 orders are placed.

Question: What is it and why? Where to look? Could this be a DB issue?