2vs2Coop Tower Bug

If both players try to build a tower at the same time on the same spot only one tower is built,
but the other player also loses his money !
It is possible that you also need to build the same tower at the same time&spot, but I can't remember that...

As far as I saw it there is no error or any other sign in the log - maybe both logs need to be compared, but I can't provide a log yet. But it should be quite easy to re-arrange the situation.