Here is a suggestion for moving you 'serial', presumably single column of labels to two columns, whilst maintaining the correct order.
The copies of the labels have an empty column first then the first column of labels then another empty column and finally the second column of labels.
The blank columns can be sized to adjust the printing positions.
Create two number sequences.
In column B enter 1 in B1 and 3 in B2
In column C enter 2 in C1 and 4 in C2
Select All 4 cells and drag down a few rows to get the alternating sequence.
In cell E1 enter this formula:
In cell G1 enter this formula:
Drag cells E1 and G1 down a few rows.
Here is a sample layout L1 to L10 are the original lables in column A starting at cell A1.
A B C D E F G
1 L1 1 2 L1 L2
2 L2 3 4 L3 L4
3 L3 5 6 L5 L6
4 L4 7 8 L7 L8
5 L5 9 10 L9 L10
Now select cells D1 to G5
Select Print and Select the 'Selection' button
Select Preview to get a preliminary look at the page.
Adjust the widths of columns D and G
You could also make this alternate lines so that you can fine tune the space between labels.
I have no idea if this will work - just a crazy idea.