I assume that the pixel size is really 10m. You can use the range finder to measure the size of pixel. Or you can look into the Geo-Coding information panel (Menu: Analysis / Geo-Coding)
Probably the up-sampled images from 60m to 10m don’t look as sharp and crisp as the 10m images, but that due the the resampling. Even if they look like 20m, it is a nice result.
@nicolas.brodu Maybe you add a few words?