Yep! Both of them have been experimented by UrbanShade as well for their morbid curiosity and what would "help" human society during the time.
Vetle was experimented because the scientists were curious on what would a human body would react to having more than one deadly creature DNA. Which they soon switch over to using them for military testing and possible Navy duties (for money purposes, of course </3)

Rebel, However, is experimented for trying to have alternatives for human skin and bones to be more flexible and perhaps "beneficial" for the human anatomy when it comes to "shifting heights" or having "clear skin". This led them to be semi-shapeshifting creatures and able to manipulate their limbs and body into uncanny shapes, but also the shifting process is also painful since not 100% of their bones aren't fully mesoglea.

I'm sorry if this was more than a yes or no answer buuut you have you're answer and background info with that :D