Internal parasitic resistance to oxfendazole and fenbendazole.

[Luckybaby]

I used oxfendazole before, to treat my chickens for parasitic worms. I bought fenbendazole few days ago, and it is due to arrive soon. If a parasite is resistant to the effects of oxfendazole, will it surely be resistant to the effects of fenbendazole? According to wikipedia, "oxfendazole is the sulfoxide metabolite of fenbendazole."

Providing a link is useful.