I have just increased from 2x1.2g tablets in the morning to 2 in the morning and 2 at dinnertime (evening). I believe they are really licensed to be taken all at once, but my consultant also said to split them if I wanted, as it's a lot to take in one go. It shouldn't make any difference as they have a 24hr effect, I believe.
I do think it is important, however, to follow the instructions about taking them with food, as their release is based on being transported to the right place with the right pH. Taking them with food obviously assists this process otherwise it wouldn't be specified.