[The Might]

this is pretty confusing
now he was Smeagol in the beginning
after he got the Ring he forgot his name, and since nobody else knew his name they started to call him Gollum name said to derive from the guttural swallowing noises he habitually made.
so Gollum is just another name for the creature

now, the two sides of his personality have names of their own - Slinker and Stinker given by who else the our good Samwise Gamgee

Slinker is Sam's name for the pathetic, whimpering side to Gollum's personality, faithful to Frodo and desperate for his approval. The 'Slinker' persona was associated with his original life as the hobbit-like creature Smeagol, long ago on the banks of the Gladden river before the Ring began to twist his mind

Slinker was his darker, more dangerous side, the one that, as they were getting closer to Mordor, started to gain more and more control of Smeagol/Gollum.

So conclusion:

1. Smeagol = Gollum

2. Smeagol/Gollum = Stinker + Slinker

3. E = mc²