Sadie our new friend...Boxer?

My family and I have Dottie our Female Boxer and Cotton Our Male Boxer, They are now both fixed after having a litter together:) WOW it was alot of fun and alot of hard work! Well we just got a female from a friend of a friend, She has not been taking care of, well not the way that she needs to be taken care of. I spoke with the friend of a friend BC she was showing signs of being preg. I was told that she just had 2 litters back to back. So this will make the 3 back to back!!! Sometimes I don't understand people but what can you do. We made an appointment with our vet but its not till next friday. I was just interested in knowing what the outcome of this appointment maybe? I have never known anyone nor have I ever breed a dog EVER back to back. Dottie was breed twice but 1 year in between! Thanks for all of your help. Sadie the new boxer has been a real joy to be around and were looking forward to this becoming her permanent home!