Would it be plausible for a planet that had an earth-like atmosphere with plentiful oxygen, but no life of any kind, to exist in another solar system?

This is a great question. 
The short answer is no.
Let me explain why.
Oxygen and all other heavy elements are made inside the stars in the process called nuclear fusion. Basically, you have lighter elements squeezed together because of an enormous amount of pressure inside the star. Oxygen also gets released by a supernova. Supernova is basically a death of a star. It's kind of poetic, without those dead stars heavy elements would stay trapped forever and you would never get components for life or anything else really. The most abundant element in space is hydrogen and hydrogen is kinda boring.
The thing is you need life to get free oxygen ( ). All of that oxygen released in the supernova is trapped inside chemical compounds, namely carbon dioxide. So you need life to free that oxygen in order to get an atmosphere that looks like ours.
Hope this helps.

Ihope you get it right bro