Background information: I am using Android 2.2 on Nexus one, running Foursquare version: 2011-01-06 downloaded from official Market.
This afternoon I checked in at a restaurant during lunch, and as usual I posted my check in status to my Twitter and Facebook via the Foursquare client. A few minutes later my friend complained to me that I am crazily flooding on my Facebook wall with the my Foursquare check-in. Here is the screenshot he sent me:

I logged in my Facebook account and found that there were at least 5+ identical check-in messages from Foursquare, except the time of the posts were having around 40sec to 1min differences from the previous one. I have no idea why there are so many messages and I am pretty sure that I only clicked the check-in button once. (In fact, there was only one tweet posted to my Twitter account for this check-in, supporting this claim). I am also pretty sure that those posts were independent posts (sometimes Facebook gives "shadow" ones...) as my friend can post different comments to each of them.
After a while I found that there were still repeatedly new posts of the same content being posted to my wall. I can do nothing but to delete all (except one) of them. When I was deleting the posts, new ones kept coming up. I have thought of revoking the publishing right of Foursquare in Facebook, but unfortunately this action was not convenient enough to be done via my Mobile browser. Therefore I have no choice but keep deleting and the flood would stop. After a while of competing with the flooding post... there were no new posts finally... thanks god. In total, I thought there were 15+ identical message posted to Facebook, one after another. BTW I have checked that the Foursquare app was closed (at least not displayed on my phone's screen) while the messagessssssss were being posted.
Please investigate and fix the issue, or else I am afraid that I have to get rid of this great tool. Feel free to voice out if I could provide any information that may help investigating.
Thanks.