Neurological symptoms can be caused by a variety of causes, among them bacteria, virus, fungus, parasites.
No one here, can tell you without doubt, that your birds do indeed have PMV virus because saying so, would be the same as saying every person with a head ache has a brain tumor.
Your birds need to be evaluated by a veterinarian starting with a fecal exam to see what if anything is revealed. You also need to evaluate the place in which they are housed with a critical eye, such as..are rodents getting into the loft or has their food become wet or moldy.
It is very important that your birds be treated for the cause of the symptoms. http://www.jstor.org/pss/30135015
I did a search for "pigeon" and "head tilt". One of the pages that came up was this one: All about the streptococcus in racing pigeons, which says: The organism can also infect the membrane around the brain (leading to poor coordination, loss of balance, or a head tilt),
IMO any disease would have more than that single symptom, but it is worth having a read as two pigeons have been affected which suggests infection.
I agree with you. Head tilting would not indicate PMV to me, and may not even have a neurological cause. An ear infection could have a similar effect. As has been said, though, a vet examination is your best bet.
Do the birds shake their heads at all, as if there is some irritant causing discomfort?