When evaluating a project with mixed $($non$-$conventional$)$ cash flows, the Modified Internal Rate of Return $($MIRR$)$ address the issue of multiple IRRs by

$$Discounting all cash flows back to year zero and then finding a single IRR.

$$Reinvesting all positive cash flows to the end of the project's life at the reinvestment rate.

$$Either compounding negative cash flows to the present or discounting positive cash flows to the end, depending on the project's cash flow pattern.

$$Utilizing both a finance rate to discount negative cash flows and a reinvestment rate to compound positive cash flows, effectively providing a more realistic measure of a project's profitability.