If you want a fixed frequency, then you want a TCXO / OCXO.
VCOs are meant to be bossed around and have no great P, V, T
stability, this is Somebody Else's Problem (those somebodies
being the reference clock, and the PLL).
Now you may find that the available 10MHz-range XOs are
highest accuracy, and rolling them up with a PLL and VCO
gets you better overall phase noise and frequency accuracy
than a natural higher-frequency compensated oscillator.
The PLL /N ratio knocks down jitter quite a bit.
A simple LC VCO isn't going to have great temperature
stability and probably will have fairly high phase noise.
The realizable Q is not that great, using spiral aluminum
inductors and MIM caps. And the lowest practical
frequency of such a design is probably hundreds of MHz
because component values can't get real big before
they eat the whole chip.
As to your example questions, "same" as in identical to
an arbitrary number of decimal places, won't happen (by
definition). If you had a tolerance / stability quantity in
mind you could analyze to it, or look at what scholarly
papers and maybe even silicon products have achieved.
But my gut says temperature excursions alone will kill
you, even at 10% allowed deviation (and good luck
with your "make" tolerances, getting that close at t=0
and all environmentals dead-center.