Error in undo

"Error performing undo: Event block has two triggered conditions. This is a bug, please report it!"[/code:18v22ggn]
Then C2 sometimes crashes, if it doesn't it gets weird.

[b]Expected result:[/b]
No error and proper undo.

[b]Browsers affected:[/b]
Editor problem.

[b]Operating system & service pack:[/b]
Win 7 Ultimate 64bit SP1

[b]Construct 2 version:[/b]
r163(64bit)