Yes. Inmates are allowed to bring their personal property with them when they transfer between facilities. Everything he has purchased or been sent during his time at Dixon can go with him, packed into what the system typically calls a property box.
The accepted items include clothing, shoes, reading material, personal photographs, letters he has received, and hygiene products. Anything that was legitimately acquired through the commissary or received through approved mail channels and is currently in his possession is eligible to travel with him.
Boot camp programs can have stricter property rules than general population units, so it is worth having him confirm with his counselor or a Dixon staff member exactly what is permitted at DuQuoin before the transfer. Some programs have tighter limits on personal clothing in favor of issued uniforms, for example. Knowing that ahead of time prevents items from being left behind or confiscated at intake.
The property he cannot bring is anything he did not officially acquire through sanctioned channels. But the photographs you sent, the books, the clothes from commissary, those all go with him.