are there 2 different spark plugs in this engine

i have a 98 with a 4 cyl. and while killing time i was reading the owners manual and there were two different plugs listed,doesnt this seem truly unusual, whats the reason for this...

Because more than one type of spark plug is compatable with an engine; some just work better than others.

iam sorry and i should have been more clear about my question...manual recomends autolites azfs32f,azfs32fe, 2 of each...i have learned one is a platinum and the other a double platinum and they have to go into the proper cylinders...i havent run accross this before

iam sorry and i should have been more clear about my question...manual recomends autolites azfs32f,azfs32fe, 2 of each...i have learned one is a platinum and the other a double platinum and they have to go into the proper cylinders...i havent run accross this before

and the answer......

of course is on contour.org (second post from the bottom)

http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=zetecmaint&Number=783022&Forum=zetecmaint&Words=spark%20plugs&Match=Entire%20Phrase&Searchpage=0&Limit=3000&Old=allposts&Main=783022&Search=true#Post783022

I run the cheap-o-motorcraft ones in my zetec, never had a problem.