Home grown status: why the double count? and why is it differnt?

[dave88]

At the player's bio, on the information part there is the home grown status, but the "club trained at" part for some reason counts double. It wont be a problem, 'cause both says need 1095 days, but the problem it counts differently. So, how is it possible that I trained a player 650 days 15-21 HG, but only just 4 days 0-21 HG? And its not just only one player but all of them.