Agree with ANSA... it might be legal in the Australian MATS, or any other ATS Unit SOP's for that matter, but that doesn't mean it's safe... and there is always an alternative solution... you just have to think beyond the square of "expected practices".
Last time I saw a particular scenario in Oz... opposite-direction traffic approaching the same VOR (180 degrees between radials). Southbound aircraft at a lower level, Northbound Medevac aircraft (MED1) at a higher level approaching Top-Of-Descent to an airstrip where the VOR was located. Instead of an early descent with a requirement to be vertically separated 10mins prior to passing, the Southbound aircraft was re-cleared outbound from the VOR on a radial that was laterally separated from the Northbound aircraft.
End result, an unrestricted descent profile for the Medivac aircraft and no delay or restriction to the Southbound aircraft... because the amended clearance to track outbound on a different VOR radial was cancelled when vertical separation was achieved with the Medivac on descent and before the Southbound aircraft crossed the VOR.
Separation Assurance and no penalty to either aircraft.
An old phrase taught to me many years ago but one that I have not heard for a very long time...
"Provision for Radio Failure"
If you or an aircraft had a complete communications failure... or deterioration to Unreadable (we experience this every day at some hour in my ACC)... what would happen?