turtle boy: It's happens when Hasbro stops using the name and another toy company then purchases the right to that name. They may not necessarily use that name (which is why you may not see another toy with the name "Bombshell" on it), but it does mean that they currently hold the rights to it.
What companies will sometimes do when this happens is to modify the name to get around it. For example, "Autobot Jazz," "Decepticon Brawl," "Autobot Ratchet," "Cybertron Perceptor," "Decepticon Frenzy" et al. Now sometimes simply adding "Autobot" or "Decepticon" to the name isn't enough - all depending on the nature of the toy and the copyright being held by the current holder. For example in most TF lines Hasbro are able to use "Autobot Jazz" but they weren't allowed to do this with Alternators - possibly because Alternators is also seen as a model car line, not just an action figure line, and the name "Jazz" probably already belongs to any toy company producing a replica of the Honda Jazz. As a result Hasbro used Jazz's Japanese name "Meister" for the Alternator.
This was probably also the case with Shockwave, unable to simply call it "Decepticon Shockwave" they called him "Shockblast" for Alternators and Energon. Hasbro also cannot use the name "Devastator" for Transformers but they can use it for Star Wars, as Lucas currently owns the name (it's the name of a Star Destroyer) - I'm guessing that could be why Energon Devastator was called "Constructicon Maximus" and movie Devastator was called "Decepticon Brawl."
Now my guess is that Hasbro are in a position where they can't get away with using the name "Decepticon Bombshell" or "Insecticon Bombshell" so they've had to come up with some other alternative - being to either change the word "bomb" or "shell" - and it looks like they've chosen the former. They could just call the toy "Insecticon," which is what they called Robot Heroes Shrapnel.
"Hardshell" isn't the best, but it sure beats "Rodimus Major." *extreme.shudder*
Avert your eyes children!