If you control Panharmonicon, do enters-the-battlefield triggers from artifacts trigger twice as well?

Panharmonicon's ability reads: 'If an artifact or creature entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.' This covers both artifact and creature permanent types, so any ETB trigger caused by an artifact entering the battlefield will trigger twice under Panharmonicon's effect.

The key rule here is CR 603.1 and 603.2, which govern how triggered abilities work — 'whenever,' 'when,' or 'at' signals a trigger. Panharmonicon modifies how many times those triggers occur by replacing the normal single trigger with two instances (CR 614.1 covers replacement and addition effects that modify how abilities function).

Note that Panharmonicon only applies to triggered abilities of permanents you control. If your opponent controls a permanent with an ETB trigger and one of your artifacts enters the battlefield, Panharmonicon does not double that opponent's trigger.

Concrete example: You control Panharmonicon and cast a Solemn Simulacrum (which is both an artifact and a creature). Its ETB trigger — 'search your library for a basic land' — triggers twice, so you search your library for two basic land cards and put them both onto the battlefield tapped.