Multiple submissions at the same time

From a UX perspective, what would be the best way of handling this scenario:

I'm working on quite a big grid that is populated by the latest saved instance of a report that our clients have supplied us with. Above the grid there is a drop down list so that the clients can chose what revision he wishes to display on the the grid.

Each time the user saves a new revision of the report it the revision with a datetime-stamp (yyyy/MM/dd HH:mm) in our database and the page does a postback that changes the drop down list to now show the latest revision as well as populates the grid with the latest save.

My question to you guys is how you would handle the (un)likely scenario of a user either doing a double click (and as such sending two revisions to the database) or if the user does two saves on the same minute (since we don't take seconds into consideration)?

Should we follow the common route of graying out the save-button until a full new minutes has gone (for the record I think this is idiotic) or post an error message and as such risk confusing / making the user feel stupid?