Two openings from inside basement to outside and not sure of the purpose
Until you said it was only 12 years old, I was going to say coal chutes for an old coal furnace. I had those in an old house built in 1910. The chutes led to a walled area near the furnace chimney (the furnace was long gone but the chimney remained because it formed part of a wall in the kitchen). The walled area was filled with dirt when I bought it, but I excavated the dirt to try to make the space useable and found it to be half full of old coal. I put an ad in the paper and someone bought it from me and removed it.
Any chance your 12 year old home was built on the foundation of a 100+ year old home?
My next guess would be vent fan ducts for a radon extraction system, the flap would be to keep pests from going in but let the air our when the fan runs.