Suppose an ettercap sneaks up on Bob the Barbarian whom is trailing his group and attacks him with a web garrote, inflicting Bob with the Grappled condition. Normally this is to the ettercap's advantage, but Bob is fine with grappling and feels the scenario is closer to the ettercap being trapped with him.
In order to ensure that this sneaky enemy can't escape, Bob wants to turn around and grapple the ettercap, to force it to hold still while Bob's allies rain pain on it from afar.
Can Bob do this without breaking the original grapple? If so, are both creatures considered to have the Grappled condition and thus have a speed of 0?