301 Product Redirects

[Verilan]

Im having an issue with the 301 redirects in prestashop on my products, Im entering the following line on my .htaccess :

redirect 301 /50-laptops http://www.need4it.co.uk/78-laptops-accessories.htm

which sort of works but when I try it makes the url :

http://www.need4it.co.uk/78-laptops-accessories.htm?id_category=50

where did the ?id_category=50 suddenly come from, has anybody else come across this issue who has a fix ?

Thank you..