I have been given to understand–and I may be wrong–that there are some alternate prayers (Collects and the like) that are in the Altar editions but not in the pew books.
Could this be what you are referring to?
Now, in the ICEL versin of the Roman Missal, at the present time, there are alternative collects. However, I think that these are going to go by the wayside.
However, in the Spanish-language Roman Missal approved for use in the United States (the one from the Mexican Episcopal Conference), alternates are not used because they are not there. I went to Mass on an Advent weekend. It was at a parish doing a novena to Our Lady of Guadalupe. The visiting priest made up his own collect (it was closely tied to the theme of his mission talk) and had the people repeat it after him. I knew this was ad-libbed because it was not the collect for the particular Advent weekday and it was geared toward his homily.
The pastor made up his own penitential rite (not any of the three approved); it was kind of like a hybrid between the confiteor and something else. It was strange.
Afte Mass, I spoke to the visiting priest and told him that while I enjoyed his homily, the improvisational collect and such was not appropriate, especially under Redemptionis Sacramentum. He said that this is what they do in Mexico (?). I told him that since he is celebrating Mass in the United States, he needed to follow the rubrics set forth for use here.
I did not know what to make of the whole thing. It gave me a headache. Providentially, I ran into the bishop three days later and told him what happened. His eyes kind of bugged out and he said that he would take care of it.
