I was only able to fill one of the tubes because my stool collector broke, what shall I do?

If your stool collector broke, you can use any clean container to collect the stool and fill the other tube.

You can provide another sample for the other tube using an old tupperware or something similar to collect the stool.

It doesn't have to be from the same bowel movement.

Just make sure the tupperware is clean and dry when you use it so you don't contaminate the sample.