Administrative Process time - visa pending

[yaghulam]

My 17 yrs old son had B1/B2 visa earlier and visited US also and that has expired. Since he wanted to visit US again he attended interview for B1/B2 visa a couple of days before, they did not refuse the visa but have sent his application for name verification, even though his name appears exactly same in his old and new passport. They said it may take one week to two months to get name clearance from concerned authority and once it is cleared anyone can take the passport to consulate and get visa stamped without another interview.

Did anyone have this situation and how long did that take for name verification.?

Please give me a clue. Thanks