it's actually come up numerous times. There are leaked chat logs where David Brock heavily implies an HRC clone was used in the debates. There's also a dude on Twitter, I think his name was realJeffreyP or something like that who was a former mega donor for the democrats (think top 100 donors in the country) and he made a highly viewed thread on twitter about how he heard Pelosi and other top folks within the democratic party describing human cloning and its active use in the democrat party (though I don't doubt it's going on on both sides of the aisle). I'm pretty sure there have been a few threads about that, search for them (using searchvoat.co) and you should find them. In the case of HRC, I personally think that both body doubles and clones are probably being used.