iTunes Store regional problem

Hello everyone, I need a very articulate answer. Next we will focus on changing the region's round-trip. I'm from Russia. My Apple ID normally based in Russian region. But I bought Viber using US Apple ID in the middle of 2014. Because Viber wasn't available for buying in RF. Then I have changed my region back to RF and forgot about it for a few months. And a few months more Viber finally hits RF iTunes Store. Of course I downloaded it again using my normally region - RF. Then I deleted Viber from iPhone and forgot about it again. But when I tried to recover Viber from purchase history I found nothing. I followed on Viber's iTunes Store page and I downloaded it for the third time. But nothing have changed in my RF purchase history. So, I can download Viber at any time and any day using RF (until it will be deleted from iTunes Store) or US Apple ID but it never listed in my RF purchase history. Like it was stuck only on US Apple ID and blocking "buying script" or something like that. By the way there's no similar troubles with songs' regional restriction. For example: I have two copies of the same song. One from US iTunes Store and one from RF iTunes Store - each of them is available in purchase history in the region where it was purchased. But songs are visible unlike the "Viber issue". Just in case I checked Hidden Purchases of my account - there is NO Viber. Tech support from RF told me that they see only one purchase called Viber performed using US Apple ID. Is this a bug, glitch or system error because I know people who first buy an app using US Apple ID and then buy again using RF Apple ID and in the end they see their app in both purchase histories. I will be glad for any help.