Shouldnt My Plants be Bigger?

Im about 5 or 6 days from starting 12/12 I would be just short of 30 days on veg. The one on the left is growing well but the one on the right has been growing slow since day 1. The one on the right I just did some training on it still it is not filling out. any suggestions?

Hey mate, i wouldnt worry 2 much, i had one that was less than half the size of the other on my last grow, produced a bit less but it was the best bud out of 5 plants. Dont forget they will double or treble their size when in flower aswell. Imagine them three times the size... And if you dont think they will be big enough just let them veg another week or 2. All the best mate.

for 30 days. yeh i'm afraid they are on the small side, what light have they been under?