Two investments with exactly the same payback periods are not equally valuable to an investor because the timing of net cash flows may be different.

The timing of net cash flows is a critical factor in assessing the value of an investment, and two investments with the same payback period may have different cash flow patterns. For example, one investment may have larger cash flows early on, while the other may have larger cash flows later. The investor's preference for when they receive cash inflows will influence their evaluation of the investments.