Mixing brand names

I have been given Cabergoline 1 mg tablets and I am increasing by one half tab
per month until I reach 4 mg.
The 1 mg tabs are brand name Cabaser.
The half mg tabs I have just been given are brand name Dostinex.
When I combined these two tablets to make one and a half mg, I was sick.
After a day or two I have started to take one and a half mg, but just using
Cabaser and I don't feel sick with them.
It would seem that combining two brand names of the same drug, Cabergoline,
gave me a sickness side-effect.