See Hartman, J. C., and Schafrick, I. C., "The relevant internal rate of return," The Engineering Economist 49(2), 2004, 139–158. for a way of identifying the relevant IRR from a set of multiple IRR solutions.
see haRtmAN, j. c., anD schaFricK, i. c., "the rELevant INTERNAl raTe oF retUrn," thE eNGiNEEring EcoNoMisT 49(2), 2004, 139–158. for A Way of identIFying tHe relevAnt iRr FROm a seT of muLTiPlE IRR solutionS.