In one building, there are 4 - 1 = <<4-1=3>>3 floors that have 5 apartment units each.
Mr. Resty has a total of 3 floors x 5 units = <<3*5=15>>15 apartment units from the 2nd to 4th floor in one building.
So, in one building, there are a total of 15 + 2 = <<15+2=17>>17 apartment units.
Therefore, Mr. Resty has a total of 17 x 2 = <<17*2=34>>34 apartment units in his 2 buildings.
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