Perfectly legal, but usually not a very good business practice.
In this case, it's part of a transition phase from one station (99.5) to another (100.9). After closing, 99.5 will, presumably, switch to the format of Ocala area sister 99.7 at which point they will have coverage of the two main population centers in the market. Since the two stations are first adjacent to each other, they actually interfere with each other so that the signal from one city cannot be easily heard in the other. Neither station would do very well by themselves, but combined, they are a pretty seemless operation from the listener's perspective. Now, we'll just have to see how the format fares.