You could reduce your accuracy by doing three tests of the same blood sample (of course, exposing yourself to the risk that the blood was taken incorrectly, was stored in an incorrect vessel, was transported incorrectly, etc...).
In terms of practicality/Insurance - this would mostly be a function of how absolutely certain we are that the tests are accurate, and how damaging incorrect results would be. If we are 99.99% certain the values are correct, and incorrectly results wouldn't result in irreparable harm - then yes, not worth the investment in redundant lab tests.
But, if there is, say, a 5% chance I might die on an incorrect test result that has a 1% chance of happening - and that test is performed 12 times/year - then you can pretty quickly calculate the net-present-value of my life versus cost of test. (I.E. If I think my Life is worth $10mm, and the test normally costs $500 each time, or $6000/year, and I need to have this test done for the next 10 years, (assuming the value of my life doesn't drop over time, to make this simpler) - then each time I get the test there is a 1% chance of failure * 5% chance of death = 0.05% chance of dying as a result of each test.
The odds of me dying then, in the next 120 test = 100%-(chance-of-not-dying-120-times-in-a-row) = 1-.9995 ^ 120) = 5.825% chance of dying in this scenario using tests that cost $60,000. If I could reduce that to 1% (4.825% reduction) chance by spending an extra $120,000 (perform the test in two extra labs) - then my my investment of $120k would return 4.825%*10mm = $482,500.
You can work the numbers, assumptions, etc.. however appropriate - but for some combination of test costs, frequency, potential harm, and value assigned to life - there is quantifiable value that justifies performing the test multiple times (and, likewise, clearly circumstances in which, even if the test results are more likely to be inaccurate, not worth performing thee test).
Not having access to multiple labs is a real problem though.