Why have more than one dog or puppy?

First of all, I didn't even want a puppy much less two of them.  Toot, my Pit Bull puppy has been with us now for over two months.  Since she was just 4 to 5 weeks old.  I remember when she just wanted to stay in one corner of the front porch room and didn't want to enter any doors.  But now after 2 months or so, she's everywhere I'm at.  She follows me room to room and have learned to jumped on the couch and my bed and lay down.  She likes to take a hold of my feet and ankle and so we decided that she needs a companion.  Another puppy.  Instead of getting another puppy from elsewhere, my daughter and her boyfriend decided to pick up her sister.  Well her sister have been living in the backyard with both of her parents and a brother. 
Suprisingly, she is very gentle, calm and really sweet.  She's been with us now for a week or so and we just love her so much.  She is totally the opposite of Toot.  Toot still have some sharing issues, but atleast she stop harassing my feet and ankles and often plays with her sister Roxie.

 

Had to take Roxie and Too to Petsmart for grooming.  Specially Roxie, she's been living in a backyard before her move to our house.  So she's full of fleas.  Hopefully this bath and nail trim will take care of them.  $10 per dog for a bath.  They both smells like vanilla an hour and half later.

 

We let them get to know each other outside while playing.

 

Toot treats Roxie as an anomaly.

 

Roxie is surprisingly sweet, for a dog who lived in somebody's back yard with 3 other pits.

 

Toot's still investigating

 

Roxie seems not to be bothered by Toot so much.