Yes, that is possible.
In The Netherlands we have DIMS, Drugs Information Monitor System (I think that was the abbreviation). http://eztest.com/labtesting.php3
They test for 10 years already and there are many pills with only as little as 15 mg of mdma in them.
I had a Snoopy once and had it analysed.
First they measure (width, height etc) it in tenths of millimeters and then look it up in the computer.
It turned out that there are about 20 varieties of Snoopys.
Some had 80 mg mdma in 'em.
Some only 10 mg.
Some had mdea only, some were mixed.
What I am trying to say is that a purple result could contain anything from, for instance, 1 mg to 200 mg.
aj