Start from what the certificate claims to measure and what the claimed measurement actually answers, because those are two different questions.
Multiple testing on the same lot reported in a single document suggests internal quality control; identical figures across different lots suggests the same certificate reused.
Concretely, the test date matters because a certificate six months older than the vial is not evidence about your material, it is evidence about what the material was like half a year ago.
The standards that exist in this space — ICH Q3A, Q3B and various pharmacopoeial chapters — are worth reading once even if nothing you test is obliged to meet them.
One qualification: a single result from a single vial at a single time is a point estimate with no error bar, and no amount of decimal places changes that.
My working rule is that a document without a lot number, a method section and a test date is marketing.
edited 23 Jul 2026 by Dr_Idris_Coulibaly — expanded the table to cover the lower concentration