In Opencart 184.108.40.206. (and probably other versions) it's possible to enter multiple Products, Categories or Information pages that share a common keyword for the SEO URL. As stated in other posts such as http://www.opencart.com/forum/viewtopic ... 40&p=26462 this has a side effect in that on the front-end you can only access 1 of those categories or products from a given keyword.
The Admin system should really include a warning if someone tries to enter multiple non-distinct keywords, otherwise they can end up with a store that doesn't function in the intended way. The response given by the Opencart team on the above link is extremely immature, and the analogy of parking in someone elses space is irrational, because in that instance you would have a warning (i.e. you could see the other car so wouldn't deliberately park where it was!). If you have a store with 1000 categories and +10,000 products, you'd need a pretty good memory to keep track of what keywords you'd used!
I would encourage this to be looked into. The principle of 1 URL mapping to one page is of course correct, but to not show a warning when potential conflicts are being entered in the Admin section is really poor. My own solution was to change the model files where the url_alias table was being written to, to check for duplicates before inserting and then appending an unique ID to the end, but it would be nicer as an Ajax function, and should really be included by default (in my opinion).