Hmm, well this is somewhat puzzling - doyenne du comice is pollination group 3 and conference is group 4, which means it flowers later than those in group 3. However, Conference is also listed as a suitable pollinator for doyenne du comice - I can't quite see how that works if they flower at different times, makes no sense to me at all.
To answer your question, in theory, no, it won't be alright, because you need two trees from the same pollination group, but in practice, perhaps it will be - not much help really, is it?

They have to be in flower at the same time for cross pollination to occur. If Conference is in bud, you'll have to use the Chelsea Flower Show exhibitor trick, and use warm air from a hair drier to get them to open.

Doyenne du Comice whilst being the best flavoured of all the pears can be difficult. As I guess the trees are still small, and I know it might be a problem, I would hunt for another pear tree planted in another location and maybe ask for a small twig which is in blossom and hand pollinate with a fine brush. This would only be a stopgap but it would work for now. The pollination groups should still work with an overlap but yet another variety might help.

Or even persuade a neighbour to plant one!