"Every philosopher has two philosophies, their own and Spinozas" Who said this

It also says "As quoted in Yirmiyahu Yovel's Spinoza and Other Heretics, Vol. 1: The Marrano of Reason. (Princeton: Princeton University Press, 1989)"

I couldn't find that text to verify it and identify the actual place Spinoza said this, and given how unreliable quote sources are on the internet, I think we ought to be cautious about the attribution.

This source is probably a better one than a random internet quote site though, so it may well be accurate, but I've seen some absolute horseshit that someone on the internet claimed to be a quote from a famous philosopher...

u/NarrowStreamer88

a letter to Brunschvicg in 1927

I've traced that back to a 1972 publication called Mélanges, edited by Andre Robinet, and if OP wants some concrete evidence, that's where they should look. I couldn't find a copy online, but I see it in various university libraries, so it should be doable, although it's in French.