Running a simulation twice can produce different outputs even when the visible settings look unchanged. A random seed can help make a sequence reproducible within the relevant software setup, but repeatability answers only one question.
Save more than the seed number
Record the software version, algorithm, input data and parameters used. A seed by itself is not a complete recipe across every program or version. Keep the original output if an exact comparison matters, rather than relying on memory of a chart.
Separate reproduction from validation
Reproducing yesterday’s simulated pattern shows that you can repeat that run under the recorded conditions. It does not establish that the model represents the real system well. Assumptions and comparisons with suitable evidence still need their own examination.
For a notebook exercise, create separate headings for “how this run was produced” and “why this model might be useful”. Put the seed in the first section. This small separation prevents a technically repeatable demonstration from becoming an unsupported claim about the world it was designed to imitate.