Just had 50 units of botox on forehead. Is this too much? (Photo)

I suspect that you had 50 units of Botox to the glabella and forehead.  I find that to be excessive given your photo and your age.  Increasing the amount of Botox that you receive does not increase the longevity of the Botox.  25 Units lasts as long as 50 units and the only improvement you will see is increase in effect of having more Botox for the same duration of time. 

The issue could be terminology.  Most injectors refer to the muscles above your eyebrows as forehead muscles but some injectors also refer to the muscles between your eyebrows as forehead muscles.  This area is a different set of muscles and is usually referred to as the glabellar area, the frown lines or the "elevens".  Perhaps the second doctor treated both of these areas for you.With Botox cosmetic, the forehead muscle in most women takes between 6-20 units, the glabellar area between 15-30 units, although both areas can take more in some women.The other possibility is the second doctor gave you Dysport.  50 units of Dysport is approximately equal to 20 units of Botox.  Dysport units tend to cost about 1/3 of what Botox units cost however.