One will probably be denied and one hopefully approved. The downside is you loose your filing fees on one of them. Always send everything to USCIS with either priority mail and delivery confirmation or Express Mail or a courier like Fedex, DHL, etc.
Yes, please have patience. The process usually takes around 90 days.
(213) 394-4554 x0 Mr. Shusterman is a former INS Trial Attorney (1976-82) with over 35 years of immigration experience. His response to your question is general in nature, as not all the facts are known to him. You should retain an attorney experienced in immigration law to review all the facts in your case in order to receive advice specific to your case. Mr. Shusterman's statement above does not create an attorney/client relationship.