Hi Jagdish,
Naturally occurring DFU's are not like minis as explained in Dr. Keene's web site here. They are hairs that are naturally close together, in line, but with a small gap in between. Normally they would be dissected into two FU's, but keeping them together can at times be advantageous.
And to answer your question, no they would not be placed so close together by making two incisions. That might be possible, but typically a doctor is distributing grafts evenly over an area based on overall density of placement, e.g. 50 grafts/cm2.
As a crude example, consider the following representation of the placement of hairs:
DFU (3 hairs placed as is, using a 1.5 mm blade) -
'll_l'
Same hairs split into two FU's using .7mm blade placed at 50 grafts/cm2 -
'll__l'
Now, getting into things like TFU's is scary and getting a bit carried away, depending on the details of how they are placed.
Gorp