The exact same
for example, I had the exact same thing
Exactly the same
for example, mine was exactly the same.
There is one ugly thing and one error in the "don't say" part of this.
"the exact same" is ugly, it's unwieldy in speech and always sounds disjointed. The result of that is that people listening to you are distracted by the use of the expression.
In the example "the exact same thing" - there is another problem: it isn't really the same thing at all. It's an item that is exactly the same (scientists and mathematicians call them "similar" but that's another story!)
The properly constructed sentence is both elegant and correct.
Click the Ad: the link opens in a new page