They are going for the same knife.

Ariadne figures this out when she sees someone coming up beside her. It doesn't slow her down any - she's moving too quickly to just stop - but her feet slip on the ground, the boots don't have enough traction to hold her upright, and she's going down before it even registers. One hand reaches up, trying to snatch for something, trying to stay upright, or at the very least, trying to take someone else down with her.