Yes, it is possible to compare an unlimited number of different variations. In a typical A/B test, two variations A and B are compared against each other.
You may however create more variations as you wish. However please note that when testing many variations at the same time, the time it takes for Piwik to reach a statistically significant result (and decide which variation performs better or worse) will increase with the number of variation you are testing. This is why we recommend to test only a few variations at the same time.