:-) No, more than just two but these are probably the best international schools. Royal Flight also have a very sweet junior school and TAISIM (I think that stands for The American International School in Muscat) runs an American curriculum school there but I think its rather expensive. I don't really know about nurseries as my children are older but I know a few friends sent their children to a nursery in a residential area called MSQ (Madinat Sultan Quaboos) which is by the British School, sorry - I dont know the name of it but its on a corner opposite Costa coffee (ish)!!
The two main schools in Muscat are The British School Muscat (BSM) which covers the british curriculum and American British Academy (ABA) which does the IB program. Both schools are well thought of in Muscat, my children attended ABA and I loved the school, very dynamic, passionate teachers. It would probably be best to get your childrens names on the waiting lists if you think you will be moving there as both are very popular.