This is true. Take a look at this point to see photos of flytraps whose rhizomes are and are not ready to be split in half:
http://www.flytrapcare.com/phpBB3/are-t ... ns#p134397
This is called dividing a flytrap. As a flytrap grows, so will its rhizome. At certain points in a flytrap's life cycle, its rhizome will literally self-divide and offshoot new plants. These two separate plants will remain connected at the rhizome and grow side-by-side, and will only look like multiple plants to an experienced grower. Several divisions can occur in a single season in some cases.
When unpotted, a full division is any rhizome that has a) More than one growth point, and b) Each connected rhizome has its own root system, whereas if you split the rhizome in half, each rhizome has roots. We call this process "dividing a flytrap"; this language can be confusing, since we are basically dividing a divided flytrap.
Here is an instructional video regarding how to perform a division of a "divided" flytrap:
http://www.youtube.com/watch?v=5l3oSsdAVcU