The age of two is the age Pim Diffy made Lloyd Diffy, when she was messing with the New Ager.
"He [Lloyd Diffy] got fired for telling his boss he made a `poopie`"
                                          -Phil Diffy to Keely Teslow

Max Joseph Tuber played two-year-old Lloyd.

A two-year-old Phil was, also, seen in a flashback of Halloween.

"...a toddler..."
                      -Phil Diffy explaining Halloween in the future