Not a glitch - I asked over at G3, and got this response from argent77:
Ah, thanks for that! It seemed clear it was expected behaviour rather than a bug, but it was still a bit of a head-scratcher.
ETA: I was aware that region scripts run constantly, so it wasn't a surprise that the second blocks in these SoD scripts were triggering. What was confusing me at that point was why the traps in the vanilla scripts - arrow traps and so on - would go off only once (I hadn't looked at them before)! Mind you, if Entered() will parse as True() only on the first occasion that an Object enters the Region in question, it would be nice if the IESDP listing for Entered() made that clear.
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ETA: I was aware that region scripts run constantly, so it wasn't a surprise that the second blocks in these SoD scripts were triggering. What was confusing me at that point was why the traps in the vanilla scripts - arrow traps and so on - would go off only once (I hadn't looked at them before)! Mind you, if Entered() will parse as True() only on the first occasion that an Object enters the Region in question, it would be nice if the IESDP listing for Entered() made that clear.