Is this a bug on this site?

This happened to me many times before. So I click the start game, while waiting for an opponent to challange me, I will also look for players who are seeking challenge. At times I will just click players seeking challange, once me and my opponent's game started, a new game will pop up suddenly( I will abort it), and will click play live chess(it will return me to my prior match, but now it used up much of my time making it hopeless in bullet chess).

You mean you accept multiple games and are annoyed multiple games pop up?

So multiple games are allowed here ? I will just start game, and will also click at someone who is looking for a challange if no one has not yet challenge me.

multiple games are allow here, not a bug. But this problem may occur by the internet connection lag or live chess time delays. There's one time I play two at a time (luckily a standard game).