You're blaming Nickelback for making songs that sound similar on a GDforum? I hate to say this, but when I started listening to GD and I borrowed Dookie from my sister, I couldn't tell ONE song apart.
For example, the melody for the song Amy, is pretty much Walking Alone and Shoplifter put together.
And Carpe Diem have the same exact chords as Burnout.
I think it's safe to say that bands that have been making music in one specific genre like GD have for 23 years or so, songs are gonna sound similar.