In nature, there can be multiple isotopes of an element, which are atoms of the same element but with different masses (atomic weights). Isotopes of an element have the same number of protons in their nuclei (which defines the element), but they differ in the number of neutrons.
For example, carbon has three naturally occurring isotopes: carbon-12 (^12C), carbon-13 (^13C), and carbon-14 (^14C). These isotopes have atomic weights of approximately 12, 13, and 14 atomic mass units (u), respectively.
The number of isotopes an element can have varies. Some elements have only one stable isotope, while others have multiple stable isotopes as well as a range of unstable isotopes. For instance, hydrogen has three isotopes: protium (^1H), deuterium (^2H), and tritium (^3H).
To summarize, the number of atoms with the same chemical symbol but different masses (atomic weights) in nature depends on the element and the isotopes it possesses.