Nothing to stop you doing this, but I would say it is more beneficial to concentrate on the game, rather than signing in and out of other accounts for a bit of bonus possession.
I had a guy a few months ago that was quite clearly using dummy accounts to support him as he did it in every game. Against me he was up to his usual trick of signing in and was so engrossed in doing it he didn't realise that two of his players had been injured early on in the game. 80 mins in before he subbed them, at which point he was 2-0 down. Had he been paying attention he could have subbed them quicker and got a better result, but he wanted to get the support so wasn't actually watching or paying attention to the match.