Count unique text values between dates

[Superform]

Hi,

So I have a list of start dates in 1 column and a list of names in another.

I am currently counting the number of start dates that fall into a range, however I also need to only count them 1 time if there is a text duplicate in another column.

So I have a 2 dates in 2 cells that are my between dates and I have this formula to calculate the number of entries that fall between the 2 dates
=COUNTIFS(B:B, ">="&A1, B:B, "<="&B1 )

A1 and B1 contain the date range

What I need to do is only count 1 x David if the date in the second column falls in the range of my dates.

So the below example would count 3

Date Range 1/1/2016 - 30/1/2016

[TABLE="width: 500"]
<tbody>[TR]
[TD]David
[/TD]
[TD]13/1/2016[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]David[/TD]
[TD]13/1/2016[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]David[/TD]
[TD]13/1/2016[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Fred[/TD]
[TD]26/2/2016[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Fred[/TD]
[TD]26/2/2016[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Sam[/TD]
[TD]29/1/2016[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Sam[/TD]
[TD]29/1/2016[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Sam[/TD]
[TD]29/1/2016[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Bill[/TD]
[TD]29/1/2016[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Bill[/TD]
[TD]29/1/2016[/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]

 

[Aladin Akyurek]

Control+shift+enter, not just enter:

=SUM(IF(FREQUENCY(IF(1-($A$2:$A$11=""),IF($B$2:$B$11>=$E2,
    IF($B$2:$B$11<=$F2,MATCH($A$2:$A$11,$A$2:$A$11,0)))),
    ROW($A$2:$A$11)-ROW($A$2)+1),1))

where E2 =1/1/2016 and F2 = 30/1/2016.<strike></strike>