Are there two possible solutions to one sudoku puzzle?

No, a standard Sudoku puzzle with a valid set of starting clues will have only one unique solution.

Here's why:

* Logical Constraints: The rules of Sudoku are designed to create a system of logical constraints. Each number can only appear once in each row, column, and 3x3 subgrid. These constraints are interconnected and ultimately lead to a single, unavoidable solution.

* Uniqueness Guarantee: Well-designed Sudoku puzzles are created with a unique solution in mind. Puzzle creators use techniques to ensure that the starting clues provide enough information to logically deduce the placement of every remaining number.

Exceptions:

* Invalid Puzzles: If a Sudoku puzzle is poorly constructed or has conflicting clues, it might have no solution or multiple solutions.

* Incomplete Puzzles: A puzzle with very few starting clues might have many possible solutions. However, with enough clues, the solution becomes unique.

In summary, if you're solving a standard Sudoku puzzle with a valid set of clues, you can be confident that there's only one correct solution.