I believe that I have a little bit longer exposure with D3200 than with the other camera. The question is what am I doing wrong? Is it that I am expecting something that is not based on a proper conclusion or is it a lens, sensor, settings or something else that causes the difference. Eventually /more theoretically than practically now, but anyway/ will a higher class body like D5100 or D7000 provide faster exposure with this lens?
I have done something wrong with one of the Pentax photos and it doesn't show EXIF data properly. The rest should be OK - exposure time is just below DateTimeOriginal in the EXIF table /but may be on different place depending on the viewer, anyway it should be somewhere in the EXIF as I just checked and I can see it/. If it is still unreadable I can upload them somewhere else because the raw files are around 12 megabytes.
Another higher level body should not give you a different exposure with the same lens unless there is something wrong with your camera. It could happen you know. I've been trying to tell you to go outside in sunlight and take a picture in manual mode, iso 100, f8 @ 1/500. then look at the picture. If you really want to, you could take the same picture with your pentax under the same conditions and then see what if so different.
Taking 6 pictures with 2 cameras under (this is where we can't help) undetermined light source will not give us any clue as how we can help.
Good luck.