I have a 29.97 MPEG1 file that has an interesting pattern when viewed frame by frame in VDub.

Frame - Frame - Frame - Motion Blurred Frame - Motion Blurred Frame....

And etc, this pattern continues, two of every five frames are quite blurry, but only where there is motion. Moreover, the two blurry frames are identical! Obviously this was the result of some kind of conversion from Film to 30 FPS.

How can I delete the duplicate frames? Using AviSynth and the SelectEvery command won't work, since there is an extra non-blurry frame every now and then which shifts the pattern. But since the duplicate frame is identical to the preceding frame, I would think it should be easy for a filter to detect.