What are the verse in the Vedas and upanishades that support dualistic philosophy of dvaita vedanta?
The most interesting thing is how Madhvacharya interprets the following verse from the Chandogya Upanishad:
6.8.7 - स आत्मातत्त्वमसि
Depending on how you split the word, it can be:
sa AtmA tat tvam asi (You are that self)
sa AtmA atat tvam asi (You are not that self)
Both are valid according to Sanskrit grammar, but since Madhvacharya thinks the message of the Upanishads is Dvaita, he will interpret Dvaitism wherever he can.
In reality interpreting this verse in this way doesn't make sense from the context this verse is in, but that's another issue.
So to answer your question, this verse is used to support Dvaita.
Other less ambiguous verses supporting Dvaita from the Upanishads are as follows:
Mandukya Upanishad 3.1.1 - Two birds, inseparable companions, perch on the same tree,
one eats the fruit, the other looks on. The first bird is our
individual self feeding on the pleasures and pains of this world;
The other is the universal Self, silently witnessing all.
Kaushitaki Upanishad - For Brahman makes him, the individual soul, whom he wishes to lead up from these worlds, do a good deed; and he makes him, whom he wishes to lead down from these worlds, do a bad deed.
Kaushitaki Upanishad - He is the guardian of the world, he is the king of the world, he is the lord of the universe, and he is my (Indra's) self.
These are just some of the verses. There are more. Also, there are more Dvaita verses than Advaita verses in the Upanishads.