This tree may not be a Marang (Artocarpus odorissimus), but another Artocarpus species or hybrid as leaf shape is not typical for that species.
Rob, this tree is grown from seed which I brought myself from Kota Kinabalu, Borneo. I ate mother fruit. I selected the seed for fruit quality and size. Before than I had dozen marangs from various sources. Chances that I misidentified mother fruit are virtually zero.
Looking at Googles images of fruiting marang trees leaves are indeed can different sometimes. I can see why you make that claim.
Common persisting misconception out there that all those rare artocarpus species are clones of one another. However they are variable, some are highly variable within species. So no surprise some would have slightly different leaf shape. This seen across other species. For example, some mango varieties leaves would be be pale green, narrow, leaf edge in a wave pattern. Others dark glossy green, big and wide, straight edge. Both would still be "mangifera indica" no matter what.