Client not deleting previous patch data after update - Large files left over from patches

So I've noticed that on some of my systems that whenever the client update, previous patch data is not deleted. It's not a huge bug but the Riot Games folder will eventually become massive because of it. Before I did a clean wipe of the game, my folder was around 9 gigs big and I always wondered why. I believe this to be the cause.

Currently it's around 4gigs, as it should be. But I had to manually remove the previous patch data.

The folder in question is under. Riot Games/League of Legends/Rads/projects/lol_air_client/releases

0.0.1.116 is the current folder that should be in there. The patcher however did not delete 0.0.1.115 and that folder was around 1 gig. I deleted the folder and the game still runs completely fine, so I take it that it's obsolete data from a previous patch.

This doesn't occur on all my systems though, but it did on one of them.