Do small preamp tubes 12ax7 need to be matched?

Just recently I purchased two early 1960’s E88CC Tubes and two Genalex Gold Lion E88CC Tubes, both sets were advertised as matched pairs.

I thought I was buying a safeguard tube with the Genalex to tie me over whilst I was awaiting the usable vintage valves to be discovered.
On testing both sets of valves to Vintage measured as good as new.
One Genalex would not produce a reading.

I personally like to have a matched measured valves to use.

Matched tubes will always give better sound.

You can "use" a 12AT7 to replace a 12AX7, in that the pin connections of the two tube types are identical, but that would be far from ideal.  The 12AT7 has less gain, a lower plate resistance, and a higher transconductance compared to a 12AX7.  In a phono stage, the difference in gain would be quite noticeable, even with high output cartridges, if one were to replace a 12AX7 at the phono input with a 12AT7.  But also the 12AT7 would function suboptimally in a circuit designed for a 12AX7, so there might also be noticeable distortion.  (I am qualifying my statements, because I know someone is going to claim that he used a 12AT7 in this fashion and it sounded wonderful.)

Mulveling mentions encountering 6SN7s where one triode tests like new and the other triode tests like its near death.  (The 6SN7 is a dual triode, with two completely independent triodes in a single glass envelope.) This can happen with a tube that has been pulled from a piece of equipment where only one of the two triodes (the dead one) was actually attached to the circuit.   Often equipment was built this way so that one could swap L and R channel tubes after the tubes seemed to need replacing, and thereby gain use of the unused section in the opposite channel.  

I am not a big believer in paying a premium for matched tubes, because tubes do not age in synchrony.  So after a few months of use, one of those two tubes may test quite differently from the other.

Lewm brings up a very good point when he states that tubes age at different rates. I have always wondered how tube matching makes a lot of sense when a) the tubes will age at different rates b) what are the parameters that one can say a tube is matched to another? c) your circuit is either driving a tube hard or it is not-- which results in varying the life and the point in (a) and lastly d) noise and distortion vary greatly by tube design and placement in the circuit.
Anyone here truly know what a tube tester is accurately testing for?

You can "use" a 12AT7 to replace a 12AX7, in that the pin connections of the two tube types are identical, but that would be far from ideal. The 12AT7 has less gain, a lower plate resistance, and a higher transconductance compared to a 12AX7. In a phono stage, the difference in gain would be quite noticeable, even with high output cartridges, if one were to replace a 12AX7 at the phono input with a 12AT7. But also the 12AT7 would function suboptimally in a circuit designed for a 12AX7, so there might also be noticeable distortion. (I am qualifying my statements, because I know someone is going to claim that he used a 12AT7 in this fashion and it sounded wonderful.)

I know it works perfectly and a person who replaced 12AX7 with 12AT7 in his new Mac preamp noticed huge upgrade in sound and (no problem with gain). They are in use ever since for more than one year for everyday listening sessions as far as I know. German military NOS telefunken are superior to any Russian tubes. My advice to OP is to stay with NOS Telefunken tubes (...ax7 or ...at7), matched pairs!