Before i could always buy a booster and get Cards i didn't have. Now some of the cards in the booster are ones i already have.

Did they change this or was i just lucky before?

In my experiance, you were not offered a booster unless there were at least 10 shows you do not currrently have that fit the category. It may be a glitch in the system. Since I have nearly all cards, I don't get offered boosters any more.

I have never heard about this, eagletsi111.
I just checked out two booster packs.
Check out the two screen shots.
I do not own any of the cards shown. It is working fine for me.
Maybe it is a browser cache problem?

Oh my!
You have less than half the cards I have.
I have 299 at the moment.

My understanding is exactly gokuh306 said.
I have all but two of the duo cards and am never offered a booster pack for duos. (for me, the page is not accessible)

@eaglets111
You wont get duplicates from a booster pack. If you already own 1 or more of the cards, the duplicate in the booster pack will be replaced by another card in the same catergory. I',m not sure if you'll get 1 of the same model, but it will be the same catergory.
You cant go wrong with the blondes boosters.

I just verified that I cannot get the booster pack for blondes.
This is pack number eight. When I click on a random booster pack and replace the last digit in the url with an 8, I get to the buy girls page instead.
That is the only booster pack unavailable to me.
There are five others.

@jonc
For the blonde booster page replace the last digit of url with 3. No.8 brings up Duo's. Thats probably why you get the buy girls page.

Sorry.
I made a typographical error that I did not see until now.
Yes, I meant booster pack number 8, that is the duos pack, which I above mentioned.
I said blondes totally by mistakes.
Check out my earlier screenshots here and you will see, in fact, that I did get to the blondes booster pack.

I have all but two of the duos, and that is why it is unavailable to me.