I've reported this before. Same situation as above: my character has Mad Dog while their character is at point blank right with me, they kill my character, I get the stars to win, but then we both lose, and the game doesn't show up in either of our match records, but it's nevertheless counted as a loss. Unlike last time, it actually said I lost, too, but same as last time, the game hanged and wouldn't move past the loss screen. Top left, you can see that I have all six stars and should apparently win, but did not. I talked to the other play after, and they reported that the game hanged as well.
The reason for the double loss is explained here (happens with festering guts as well). The fact that the game hung for both of you does seem problematic though.
Wait so... you cannot rely on festering/maddog for a suicide victory if you don't start the explosion with a living ally? and it matters not if that ally would have died from the explosion? What about when the festering/maddog cascades with the opponent (inactive-player)... can a cascading explosion work in reverse i.e. kill the character who originally exploded leading to a counter-victory? and what if the only living ally of the opponent dies from the first explosion, would they still count as a living ally for the cascading explosion?
Thanks for the link, Scarponi. You posted that over a year ago: too bad they still haven't fixed what seems like an obvious bug (especially considering it screws up your match history as well as can cause problems for future matches).
Interestingly, a person talked today about a similar occurrence with Festering in world chat today (a player named gzusluvu), but mentioned that it was their fourth match in a league game...but it let them play a fifth match because it thought he never played the fourth match. That seems inconsistent: when I've had the Mad Dog double loss, it's taken away my league game and treated it as though I had lost. This person said it treated them as if they had never played it at all.