It's possible that yours is different, but of the locking collars I have seen, they all have only one set screw. The other hole is to use a long punch to set the collar on the bearing, or rotate the collar to remove the pinch fit from the bearing to release it from the shaft.
The bearing and collar are machined out of round to make locking fit on the crankshaft.
Another thing to pay attention to at assembly is that the bearing has a snap ring inside the ID. It is what sets the proper depth of the bearing mounting position on the shaft. This in turn will allow your long pointed set screws that screw into the pulley to land in the proper position. The proper position is behind the bearing, not on it. This keeps the pulley from walking off the bearing in use.
Mike
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