You have a few misconceptions.
Characters in portraits CAN interact with the real world via speach with what we'll call "echo memory".
Characters in portraits can move between other portraits of themselves, and other portraits in the same building.
Pictures CAN NOT talk, they can simply wave, smile, motion.
“and a boy in my dormitory said if I develop the film in the right
potion, the pictures’ll move.” Colin drew (key word move, not talk. )
ONLY 1 instance of a person in a portrait exists at once.
Unlimited instances of a person can exist in a picture at once.
Gilderoy Lockhart came slowly into view, seated at a table
surrounded by large pictures of his own face, all winking and
flashing dazzlingly white teeth at the crowd.
To sum this all up, the portraits that contain "echo memory" (which includes memories, the ability to speak and interact) are a single instance with multiple frames. It's not 2 separate portraits of Phineas Nigellus, it's 1 portrait of Phineas Nigellus in 2 locations. He has to physically enter his other frame to be able to see out of it; he can't have 1 copy of himself in one frame and 1 copy in another and have them both share memories.
Based on this (and the fact that taking pictures is a far less complicated procedure than painting and would likely not retain the memories of the person captured), a person in a picture does not share a consciousness with any other copies of that picture or any other pictures of that person.
To confirm, via Pottermore
Hogwarts portraits are able to talk and move around from picture to picture. They behave like their subjects. However, the degree to which they can interact with the people looking at them depends not on the skill of the painter, but on the power of the witch or wizard painted.
When a magical portrait is taken, the witch or wizard artist will
naturally use enchantments to ensure that the painting will be able to
move in the usual way. The portrait will be able to use some of the
subject’s favourite phrases and imitate their general demeanour. Thus,
Sir Cadogan’s portrait is forever challenging people to a fight,
falling off its horse and behaving in a fairly unbalanced way, which
is how the subject appeared to the poor wizard who had to paint him,
while the portrait of the Fat Lady continues to indulge her love of
good food, drink and tip-top security long after her living model
passed away.
However, neither of these portraits would be capable of having a
particularly in-depth discussion about more complex aspects of their
lives: they are literally and metaphorically two-dimensional. They are
only representations of the living subjects as seen by the artist.
Some magical portraits are capable of considerably more interaction
with the living world. Traditionally, a headmaster or headmistress is
painted before their death. Once the portrait is completed, the
headmaster or headmistress in question keeps it under lock and key,
regularly visiting it in its cupboard (if so desired) to teach it to
act and behave exactly like themselves, and imparting all kinds of
useful memories and pieces of knowledge that may then be shared
through the centuries with their successors in office.
The depth of knowledge and insight contained in some of the
headmasters’ and headmistresses’ portraits is unknown to any but the
incumbents of the office and the few students who have realised, over
the centuries, that the portraits’ apparent sleepiness when visitors
arrive in the office is not necessarily genuine.
