I have 'heard' that when purchasing TT's you should try and get sisters, TT's that have sequential serial #'s so that quality is assured, is there any merit to this?

Well it seems logical. If the serial numbers match (or are sequential), you are almost ensured the components used are of the same week/day, so you'll have minimal fluctuations in specs.

It's like you would buy paint. If you buy two pots of one color with same serial number, you are sure they are manufactured the same week/day, so with the same color ratio's. If you happen to buy the same paint one month later, chance is the color will differ slightly, because the ratio's may have changed a little in the factory by then.
Same thing with electronics.
But nowadays the big companies like Technics or Vestax can manufacture their equipment pretty precisely, so even if the serial numbers differ, the differences will be almost inperceptible.

I dont think it honestly matters.. the tables shouldnt be different in any way no matter what serial #.. as long as they both were manufactured around the same time

Even if they were manufactured a few years from each other it shouldn't matter. If they're industry standard, uniformity and quality control should (and must) be a guarantee.

___________________
Melodic Progressive.

Better than sex.

yeah you're right, considering the price of turntables, they should all equally be top quality no matter when made, or sequencial #'s or anything else.

I think it would be more of a bad idea than a good one. If they're both made on the same day and on that specific day there was something wrong with a certain component they ordered (or made), then both your tables will be screwed, as opposed to just one. There isn't too much that can go wrong with TT's (especially new tech's, but it has happened b4). Anyways I thought I'd just give a different opinion.