The slip joint is common among a lot of designs. This is an alternative of the same type of design. Is it a bad thing? Meh. It kind of depends on how well they fit. They could slip on nice and seal well or suck for fitment and leak depending on how well they were made. With a good brand the consistency is much better. These cheap headers are all about throughput and sales numbers. Some will be good, some will be junk, and then there will be many somewhere in between. The variance in manufacturing will be much higher.
Perrin's pretty big about putting their name on everything. If it was Perrin at all, there'd be Perrin logos on the thing plain as day.