Count Unique Values within date range

Forum Guru's,

I'm having difficulty figuring out how to do some counting as the column I would like to count has duplicates and I simply need the unique values.

Below is the formula I use to simply count how many total records fall within the specified date range. The date range is contained in I7 as the start date and K7 as the end date.

The data being counted is housed in a separate tab, Weekly Pre-sale Physical.

=COUNTIFS('Weekly Pre-sale Physical'!$I$3:$I$173,">="&I$7,'Weekly Pre-sale Physical'!$I$3:$I$173,"<="&K$7)

In column B of that tab, we keep a list of serial like numbers (29730) that I would like to count, based on the date range above and only unique values as we may list that serial number twice.

I've tried all of the Unique Value formula's I can find but can't seem to accommodate for the "date range" as described.

Any thoughts? Thanks in advance!