Believing In Alternative Single God
What do you mean by alternative single God over Allah? There’s only one omnipresent, omnipotent, omniscient, omnibenevolent Creator that we refer to as Allah. There’s nothing over Him.
I think any entity that meets the criteria set in surah Ikhlas is Allah. Calling him with any other good name doesn’t make a difference. Since Allah is the same, perhaps the person making the distinction may be saying that he believes in another Allah with the same properties, but then perhaps he doesn’t believe in prophets or holy books or angels or the last day. As all these are associated with Allah’s belief.