Because for the first one the opponent has got away from him, with the ball, and he has pulled him back. Obviously a still doesn't show this, but it was also much more of a hold than the second one, and was textbook SPA.Incident 1 - caution
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Incident 2 - no caution
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Not sure why one is being cautioned and the other isn't? And if I'm not sure, then to non-refs it will certainly look like it should have been a second caution.
Whereas on the second one he doesn't have the ball, and has pretty much zero chance of getting it even without the holding. The two simply aren't comparable.