An anemone is going to move to where it thinks is the best location. Some will move between two different places depending on time of day. Your anemone's of course, could be simply growing towards the same 'best position' as the purple tips in our 150g tend to grow quite quickly
Depending on the size of tank, lighting, and other possible inhabitants will regulate how many and of what kind of anemones you can have together.
In our 150g, the purple tip and bubble sit almost right next to each other under the single 400w MH
pendant... no problems after a month.