17 R4, choose Boot device from two SSDs?

I have an Aleinware 17 R4. I have two Samsung Evo M2 SSDs. One is the EVO 850 and one is the EVO 860. When I got the 860, I cloned the 850 and then pulled the 850 out of the laptop. (I was having problems and wanted to see if they were hardware related). Now I would like to add the 850 back into the system and either A) format it to use as a data drive or B) put a Linux OS on it so I can have a dual boot system, My problem is as soon as I add the 850 back into the system, the Alienware boots from it, making it the primary drive, and does not show the 860 as a drive. I can go into disk management and see it, but Windows ignores it. I even interrupt the startup and go into the boot menu, deliberately choose the 860 from the menu, and the laptop still boots off of the 850! How can I have both of these SSDs active, and how can I choose which drive is used as the primary boot?