I have heard about cloning but assumed it would be a complicated process. I just went Googling a learned some interesting facts. Sounds like it is growing rampant...especially in the drug trade. Cell providers claim they are losing $600-900 million annually in the US. Example: I pay $45.00 monthly for unlimited calls and 5GB data. I normally use only approx .5/GB data monthly as I am usually using a wifi connection for data. I could have a gf/wife clone a different phone using my cell phone data. It would appear to my cell phone provider only 1 phone was using their service towers. As long as gf/wife cell and my cell didn't exceed the 5GB data I wouldnt know, but more importantly, the cell provider wouldn't know, therefore saving my gf/wife from a monthly cell phone fee. In essence, it would be the same as if you had a neighbor living VERY close to you, say maybe a condo with a shared wall. If someone ran a coaxial cable from neighbor to your house you could eliminate a monthly cable fee. But w cloning it is all done wireless. But more importantly, the cloner would have access to the true subscribers stored cell data. I am guessing this is becoming a huge problem for cell providers and they are working silently behind the scenes to solve this security/fraud issue without bringing notice to current potential.
https://www.movzio.com/howto/cell-phone-cloning-guide/
https://www.movzio.com/howto/cell-phone-cloning-guide/