its a grafted tree - the low version maple is the graft or scion - the high version maple (trunk + root system) is the rootstock
should be able to see the actual graft point - can appear as a horizontal line or ring circling the trunk, a step-up or step-down or appear as a stylized lightning bolt both circling the trunk
if you cut off below the graft, the low version is gone forever -
if you want to preserve the low version maples appearance, cut out the tall version .....chances are it will sprout another, and another - clip off as they appear, and maintenance will be minimal
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