פירוש על ברכות 60:3

They must accordingly have been the morning and additional Tefillot, and thereby he acted contrary to the view as stated in the Mishnah.

I.e. he said the morning Tefillah twice, and not the additional.

R. Johanan was a very eminent Rabbi, and he clearly intended to imply that R. Jannai did say the additional Tefillah.