Mailbox in 2 databases after Move

Exchange 2010-SP3, Rollup7. Running on vSphere, Server 2008-R2

On September 26, 2014 I moved 2 mailboxes from MB1 to MB2 as a test.  The next day I moved the mailboxes back from MB2 to MB1.  I ran this PS script:

Get-MailboxStatistics -Database "MB01" | Sort totalitemsize -desc | select Database, DisplayName, TotalItemSize

Get-MailboxStatistics -Database "MB02" | Sort totalitemsize -desc | select Database, DisplayName, TotalItemSize

The users mailbox shows up in both Databases.

My Questions:
1. Will the mailboxes under MB02 delete once the retention period has expired?
2. If the mailbox is on Litigation Hold, will the retention be ignored, thus leaving the mailbox in 2 databases indefinitely?

Thanks.