It's unlikely that a decision has been made yet about your paper. At least in the sorts of conferences I'm familiar with, no decisions are made before the program committee meeting (except possibly eliminating completely inappropriate submissions, such as crackpot or off-topic work). This means all reviewers are recruited before any decisions are made, since all the reviews are needed at the meeting, so being asked to review supplies no information about whether your submission will be accepted.
The only correlation is that you shouldn't be asked to review something too close to your own submission, to avoid conflicts of interest. If you are worried about that, you could always ask the program committee member who recruited you as a reviewer. It's possible that they just screwed up, without realizing the potential conflict, but it's more likely that they think this paper is far enough from your submission to be safe.