Every print run produces a new barcode. Even if the same equipment and materials are used there will be minute differences in the machine settings, batch or mix of inks, variations of plate or roller pressure, wear and tear of the equipment and plates, reflective properties of the paper or other substrate, or the ambient humidity or temperature of the printing premises. Even subtle changes in these variables can affect the results.
Given there is always the possibility of small changes between test samples and production runs, we recommend you aim for a clear pass with your test sample. If you only achieve a marginal pass, going ahead with a full print run could be a risk.