filtering one table based on if multiple values exist in another table

I'm have two tables in my data set

and 

I need to create a report view that will show me the Manager value in the first table, only for values where i have multiple options in the second table.

So in the case of the tables above i want to see the value for manager because user1 and user 2 have values a and b.

I don't care about Manager 2 as their associated users all have value a.

I already created a table relationship using the user column in the first table as the primary key.

I'm not really sure how to ask the question for a google search on this one so hopefully someone can point me in the right direction.