According to our current understanding of particle physics, all protons are considered identical to each other. This concept is based on the fundamental principle known as the "indistinguishability" of particles of the same type.
According to quantum mechanics, particles such as protons are described by wave functions, which contain all the information about their properties. For identical particles, these wave functions must be symmetric under particle exchange. This means that if you were to swap two protons, the overall description of the system should remain the same.
Experimental evidence, such as scattering experiments and measurements of proton properties, supports the assumption of proton indistinguishability. Protons have consistent and repeatable properties, and they behave in a manner consistent with this principle of indistinguishability.
That being said, it is important to note that our understanding is based on the current state of knowledge and experimental observations. There is always a possibility of new discoveries or more precise measurements in the future that may reveal previously unknown differences between apparently identical particles. Scientists are continually refining their experimental techniques and pushing the boundaries of knowledge, so it is always conceivable that extremely small differences, beyond our current detection capabilities, could be discovered. However, based on our current understanding and the extensive experimental evidence, protons are considered indistinguishable from one another.