Why Does My Glock 19's 9mm Sig Sauer 124gr FMJ JHPs Tend to Overpenetrate Target Pasters at 15 Yards During Nighttime Shooting Sessions?

I've been messing with my Glock 19 lately and I've noticed something weird with the Sig Sauer 124gr FMJ JHPs I'm using. At 15 yards, during nighttime shooting sessions, I've seen the rounds consistently overpenetrate the target pasters. Now, I know what you're thinking - "overpenetration" is bad, right? But hear me out. I'm not seeing this with my other ammo, just these specific ones. I've checked my zero, my sights are clear... I'm stumped. Has anyone else noticed this with their Glocks or other 9mms? Am I just being paranoid or is there something going on with these bullets?