Your experience is not unusual and indicates that you probably have a very good, up-to-date urologist! During your first TURB the urologist was taking samples where they thought the cancer might be. When the results of the first TURB were in, they saw that there might be areas that deserved further attention so on the second TURB they will know exactly what areas to sample.
In my case, the first TURB showed papillary carcinoma, but also areas of "undefined inflammation." My urologist felt that it was important to take a closer look at these questionable areas and, sure enough, the second TURB pathology report mentioned CIS which is always high grade. Therefore I underwent two years of BCG/BCG maintenance and fortunately have been cancer-free ever since.
I do not have the data in front of me, but it is considered good practice if there is any uncertainty for a urologist to do a second TURB and it is definitely not unusual. I know you do not want to go through this again, but be glad that your urologist is so vigilant. When this is over you will KNOW that the results are as accurate as they can be.
Good luck and let us know the result!
PS I just noted your second post where you stated that you had a recurrence after just 7 weeks. I doubt that this is the case; the second TURB, as noted above, is really just an extension of the first situation!!
Sara Anne