i don't believe IP rights are applicable in fashion... hence the trend where you see all the designers converge on similar pattern and cutting season after season...
however, if it looks so identical that it can be passed off as Hermes, then it is riding on the coat tail of the marketing and branding power of Hermes. in this case, the "birkin" bag from Kwanpen, imho, does follow that.
i have just visited their store today and bought a few items. the croc skin are mostly niloticus and are very well made in gorgeous colors. upon closer inspection, a savvy H user would be able to tell that the "kwanpen birkin" is not hermes at all. however, most public probably wouldn't. so, it is up to each individual discretion and right (as a consumer) or whether s/he wants to buy the bag...