It is not "Compulsory" though best results (lowest distortion) are obtained with Output Transistors of approximately equal current gain (hfe).
If the gains of the output transistor are unequal, the Output Transistor with the higher current Gain should be used as TR-1.
Do note that no catastrophic failure4 will result even if you use Output Transistors with significantly different Hfe.... Only distortion will be slightly higher.
There is a Good Site devoted to this amplifier & circuit, including the original article (attached) in the April 1969 issue of Wireless World.
The original article also discusses in detail, the use & effects of un-matched output transistors.
I have used 2N3055 devices as the output transistors, without any matching, and the results were sonically very good to my ears
