Identity of a particle in quantum physics

Philosophical Investigations-Wittgenstein, para 215. But isn't the same at least the same?
We seem to have an infallible paradigm of identity in the identity of a thing with itself. I feel like saying" here at any rate there can't be variety  of interpretations. If you are seeing a thing you are seeing identity too."
Then two things on the same when they are what one thing is? And how am I to apply what the one thing shews me the case of two things?

Take the case of single electron going threw two slits, how do we know it is the same electron the emitter emitted that strikes the detector? Our intuition, we emitted a single electron, we design the experiment so that outside electrons can't come in, like when you roll a marble in a opaque tube, you expect the same to come out. There's another way of doing it like watching the marble move through a transparent tube. Here you watch the marble move. The identity of the marble is fixed and not changing. There is a difference between the two methods.
In the first method identity is fixed, and in the second method the identity is vague, but we use our intuition to get the identity.

A particle behaves like a particle when the identity is fixed and it behaves like a wave when we use intuition to identity the particle.

When identity is fixed we know that the same particle moves. And in the other case, it is the negativity, like "this cannot be any other, therefore it is the same particle", we use logic to make the identification. The other case it is physical, you can touch and see the particle all the way.

In the second case an observer is present, whereas in the first case observer is absent.