Another way to do this would be to make copies of the problems you're using for the set and to change the randomization so that it isn't random. For example, suppose we wanted to use Library/NewHampshire/unh_schoolib/Ratios/riosrs202.pg, which has the following randomization.
$aa=random(39,43,1);
$a=$aa/100;
$n=64*$aa;
$n1=$n%10;
if($n1<5){$x=0;} else {$x=1;}
$ans=(($n-$n1)/10 +$x)/10;
We could create a new copy of this problem---I would be careful about naming if we're changing the randomization, and call it something like local/nonrandomset1/prob1.pg. And then we could change the randomization to not be random:
# $aa=random(39,43,1);
$aa = 41;
$a=$aa/100;
$n=64*$aa;
$n1=$n%10;
if($n1<5){$x=0;} else {$x=1;}
$ans=(($n-$n1)/10 +$x)/10;
Then if we use this problem in our set, all students will get the same version.
Hopefully that makes sense and is useful,
Gavin