It's the overall end-to-end length that matters most--along with
elevation above ground and some other effects. If the center insulator
is one of those ceramic "eggs" so the two wires form intertwined loops,
you might end up with a couple pF extra capacitance, which is over 2000
ohms of capacitive reactance at 30MHz and even less effect at lower
frequency. You're really unlikely to notice that in a dipole near
half-wave resonance (low feedpoint impedance), though for full-wave
resonance with small wire diameters (high feedpoint impedance) you
_might_ be able to detect the effect. But if you're feeding with 450
ohm line, you presumably are using a tuner, and why on earth would you
be worried about it?

Cheers,
Tom