A very good question. Technically bigamy is illegal in the U.S., but I'm not sure if they would actually enforce it if you tried. I'm told that the Sultan of Brunei has a compound of houses here in Las Vegas and routinely brings his wives here with him for visits. If you mean that you plan to bring them separately, then assuming they issue the visas, you should be okay. Otherwise, I have no clue what the immigration officers will do.
Very interesting question. As you and your wives are entering the US as visitors, her B visa is actually independent of your B visa. In other words, your non-immigrant visa status is unrelated to hers, she is not a "visa classification dependent."
You certainly should be prepared to answer the question if it comes up at the port of entry.
If anyone requests immigration benefits under public policy one one person can be designated as spouse no matter what the legal relationship in the other country may be. Thus, immigration visas where by a person petitions as a beneficiary a spouse is limited to one. It would be advisable for you to contact an experienced immigration attorney before completion fo the application for B2 visas for an examination of your options. It is important that there can be no fraud on any of the applications and it may be possible for each significant other(s) to apply separately with an affidavit of support. Good luck.
Legal disclaimer: The statement above is provided by CC Abbott is based on general assistance and not intended to be a legal opinion because not all the facts are provided. The person requesting information and all others reading the answer should retain an attorney who is permitted by the state bar within the jurisdiction who can examine the complete facts and provide a legal opinion on your case. All information provided in the above answer and other information provided by CC Abbott does not create an attorney/client relationship within any state of Federal law.