They could be.
Several varieties look very similar to Kieffer, and your picture looks like they could be Kieffer. I was surprised this year at how much Kieffer and Moonglow resembled each other in my yard. In years past I felt the difference in looks was a bit more distinct, but not this year. Kieffer seemed to have more of a "blush" than normal, and Moonglow seemed to have less. Also the size of Moonglow is normally larger than Kieffer, but this year they seemed about the same.
My Kieffer Pears are falling right now. There may be 15% of the pears left on the trees. Moonglow doesn't hang quite as long, but I saw a few of them still hanging the last time I looked. The drop time will vary by region of the country, but they are pretty much on track this year in my area.
You also see pear trees being sold as "Improved Kieffer" but they don't tell you what has been "improved." I've seen the pictures, and they look just like Kieffer to me. Could they have improved the taste but lessened the disease resistance???? Who knows???
If that tree you found has fireblight/disease resistance, I wouldn't care if it was a Kieffer or not. I would rate it a good October dropping pear and graft it if it was something I wanted.
Best Wishes - Steve