I have two ongoing T-5 BI’s, one for a DoD position, the other for a non-DoD position. Both say they can’t close their BI until they get the other agencies BI. No idea why since they asked the exact same people the exact same questions, but regardless it seems like some sort of infinite recursion problem? If the BI isn’t closed they can’t send it off to another agency, but the BI can’t be closed without info from the other investigation. Wondering if anyone’s ever had this problem and how long it took to get resolved? Should I just drop out of processing for one of them? Seems like it’d make it simpler. 
I’m also having two BI’s done with similar agencies. My first one has closed and I’ve been in adjudication for a long time and my second one is still active waiting on the NAC check (they need my file from the first BI), however, I’ve been waiting in this stage for 6 months now. My references were contacted long before that. I also fear the first agency won’t give up my file to the second agency until I’m completely done with their process, or even worse both won’t clear me until the other is done. I get what you’re saying about the infinite recursion because I feel like that’s what’s going on with my processes. Hopefully someone can chime in and give us an answer.
Haha yeah it’s a bit frustrating. I asked if they could just combine the BIs into one to save taxpayer money and they laughed at me and said no. Gotta love the government.