Here is already a different matter. Although using "tę" is the most preferable by linguists, the "tą" is also regarded as correct - and is widely used alternately in Poland.
In everyday speech it is allowable, but it shouldn't be used
sjp.pwn.pl/poradnia/haslo/te-czy-ta;2227.html
kul.pl/te-czy-ta,art_20689.html
It is a very common error among native speakers, so you are right it's likely to become a correct form in the future.
In terms of "obydwoma sprawami" - it's clear that it's an error, don't speak nor write like this. The media - and, especially, politicians - rarely bother of this. It is also common, for example, to say "w roku dwutysięcznym piętnastym" ("in the year two thousand fifteen"), although the correct version is "w roku dwa tysiące piętnastym", like we say "w roku tysiąc dziewięćset dziewięćdziesiątym ósmym" ("in the year nineteen ninety-eight") and not "w roku tysięcznym dziewięćsetnym dziewięćdziesiątym ósmym" nor "w roku tysiącdziewięćsetnym dziewięćdziesiątym ósmym" (in case of 19... there weren't any problems, they appeared with the new millenium).
Also weakly educated people may tend to omit this ć in the spelling of the numeral 90 (dziewię
ćdziesiąt) since it virtually doesn't appear in the pronunciation (it is normally pronounced as "dziewiędziesiąt"). Similar situations, where a letter from spelling is omitted in speaking for simplification, are the order of the day in English, but in Polish they are rare. For example in English "drawer" as a name of a part of a piece of furniture. As far as I know, the ending "er" shouldn't be pronounced (unless we mean a person who makes drawings). Could anyone explain why?