Even if one recites a Berakha (blessing) which is not required, in a language other than Hebrew, one still transgresses the commandment of not taking G-d's Name in vain (Shemoth 20:7). One may not cause a situation which will require an additional blessing to be recited unnecessarily.
For instance, one may not tell members of one's household not to bring all the fruits out together, so that one will recite a blessing each time new fruits are brought out. This is forbidden, even on Shabbath where we need to make up the number of blessings in different ways, such as smelling Hadas (myrtle) and the like.
If someone made a Neder (vow) to fast, and forgot, and said a blessing and put the food in his mouth, and only while chewing, remembered his Neder, he must spit it out without swallowing anything. In this case he must not be concerned about having said G-d's Name in vain. However, since he did do so, he must say the verse of "Barukh Shem...".
(See Kaf Hahayyim, 215, Oth 27, 28, 30, 31)
Taking G-d's Name in vain, vowing a neder not to eat, berakha lebatala in la'az