Keep the original quote, identify its date and source, and record the exact difference alongside the relevant current official material.
Preserve the history while resolving the present issue
Do not overwrite the earlier document and lose the explanation for a discrepancy. If the difference affects an actual submission or payment, clarify it through the appropriate process rather than selecting whichever version is more convenient. Identify who actually produced each version being compared: a figure or description that came from an adviser, a broker, or another intermediary is not the same as one published by the official government source, even when both are labeled with a similar date.
Only the current official material controls the requirements in effect now, so an earlier estimate from a non-official source should be labeled as exactly that rather than treated as a prior official position that later changed. A dated printout or saved copy of the official material as it existed at the time of comparison prevents a later dispute about which version actually applied. Where an intermediary's earlier description turns out to differ from the government's own current material, that difference says something about the intermediary's accuracy, not about the program itself having changed twice.
Keep the source of each document as part of its own record, not just its date, so the comparison being made is always between things that are actually comparable.