Are two felony drug convictions counted as two strikes under CA 3 strike law

Drug felonies are GENERALLY not strikes, unless they involve giving or selling drugs to a minor. (See Penal Code sec. 1192.7(c)(24). He should ask his lawyer about the specifics.

How old was your son when these crimes were committed? There is current litigation over whether juvenile crimes can count as strikes. The argument is that juveniles aren't entitled to jury trials, hence there is a due process violation when the district attorney/courts use a juvenile adjudication (if he was tried as a minor, then its an adjudication, not a conviction) to enhance a future adult offender's sentence. Nearly all the juvenile cases I handled that involved serious or violent crimes were taken to trial because of this uncertainty.
The case to watch is: People v. Nguyen (2007) 152 Cal.App.4th 1205 [62 Cal. Rptr. 3d 255].

Hard to tell based on what you have posted. Have him discuss this very issue with his attorney. Good Luck!