gpt-5-6-thinking (2)

If you’re referring to gpt-5-6-thinking (2):

gpt-5-6-thinking is a backend-style identifier associated with GPT-5.6 Sol using reasoning/thinking. OpenAI’s current ChatGPT documentation describes GPT-5.6 Sol as supporting selectable reasoning levels such as Medium, High, and Extra High. (help.openai.com help.openai.com)

The (2) is not part of the model name. It’s most likely a duplicate/count suffix added by whatever UI, tab, file, or log you copied it from.

And for this conversation: I’m GPT-5.6 Sol.