Double Overcharged Systems

Overcharged Systems: "All start of turn effects during the environment turn also act at the end of the environment turn."

If two copies of Overcharged Systems are in play, does that mean that the start of turn effects happen *twice* at the end of turn?  I think not, but was uncertain enough to want confirmation.

They will only act once at the End of Turn.

Oh, really? I guess that makes sense, but I’ve been playing it wrong then.