I have had the same problem with my multi.log file being almost 100MB. When this happened I had been using both the BtRL launcher from the demo and 3.6.9 launcher 5.5c. I started by playing against a friend, me on my laptop and them him on my desktop, hosting. He was using the BtRL launcher and I was using the standard one. We finished playing due to a myriad of errors such as "A pilot with this name is already ingame". We stopped and I tried to host a game when Hippo's server went down, and then went onto his when it came back up. He couldn't play from my laptop and had to get home so I just played on Hippo's. I started getting the double respawn message, I would click it after dying and then it would appear under my HUD afterwards. That stopped appearing after a while and I played as usual, and then had to go.