Wiring the two speakers as you have, in parallel, generates a 4-ohm load. That
means each side of the amp is driving 2 ohms. For most amps that would be a
disaster; and they would go into protection, or combust. However, the specs on
your amplifier say that it's okay; it's rated for a 2-ohm load in normal mode,
or a 4-ohm load in bridged-mono mode. And an 8-ohm load would be fine too.

So you're okay. However, do NOT try to add any more speakers in parallel to
what you already have!

Peace,
Paul