I have no knowledge of Fomadon P; however, even for nearly identical developers (say, Kodak D-76 and Ilford ID-11), you'll sometimes find differences in development times for particular films by the developers' manufacturers. This is usually explained as being caused by different testing conditions or criteria for "proper" development between the developers' manufacturers. It's conceivable that Fomadon P is based on D-76 and that this is what's going on.
OTOH, the difference you cite is almost a 50% increase in development time, which is rather hefty for this explanation, unless perhaps you're looking at different dilutions or developing temperatures.
In any event, you should consider the development time figures for any film/developer combination to be suggested starting points, not written-in-stone values. You may need to adjust the times based on your own agitation style, metering/exposure, personal preferences, etc. If in doubt, shoot a test roll or two to determine if the suggested development time is reasonable.