>OT God and NT God are different beings
Wrong
Jesus himself said
>17Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them, but to fulfill them. 18For I tell you truly, until heaven and earth pass away, not a single jot, not a stroke of a pen, will disappear from the Law until everything is accomplished
The law and prophets being those of the OT. Why would the other NT God acknowledge the correctness and rightiousness of the law of the false God?

Also Jesus is High Priest in the Order of Melchizedek. Now who is Melchizedek?
>18Then Melchizedek king of Salem brought out bread and wine—since he was priest of God Most High— 19and he blessed Abram and said: “Blessed be Abram by God Most High, Creator of heaven and earth,
So Jesus is the high priest of the order that worships the OT God.

We also have Jesus quoting the OT to make a point and fulffilling the OT prophecies.
Jesus name even means "YHWH saves"
There is no way to argue that NT God is another from the OT.

Usually the people claiming OT and NT are to be seperated claim that OT God is evil and Satan (Demiurge) that trapped us in this world.
If this world would be created by something evil, then why is it so beatiful? Why is it abbundant with ressources, food and drink? There is more than enough for everyone and its only through the corruption of a few, satan worshipping pedophiles, that we experience scarcity. So the creator is obviously good.