I'm wondering if it's against site rules or some unwritten stats.stackexchange.com etiquette.
If it's not I'm wondering if it's considered to be appropriate (in the sense of wise) to make a second bounty.
Clearly some questions are so ill-formed that they have no chance of being successfully answered, and so creating another bounty would just waste reputation points. I'm not well-informed enough to know for sure if my bounty question was one of those, but I suspect it was not hopelessly ill-formed, although it was also not a very interesting question, as it related to a rather specific research scenario. However, I wonder if the extra points (me chucking in 200, say, instead of the 100 I already put in) are likely to make a difference.