Two units of the same model can carry meaningfully different real-world warranty coverage. The variable is when the warranty clock starts.
Manufacture date vs purchase date
Most PV warranties run from the manufacture date, not the day you install. Older stock — even sealed and unused — has already spent part of its warranty life on a shelf. That's fine if you know it and price it in; it's a problem if you don't.
The inverter exception
Some manufacturers start the clock differently. Huawei, for example, can begin the warranty six months after goods arrive in Europe. So the same SUN2000 can have a different effective coverage window depending on its route to market.
What we do
We treat manufacture date as first-class information and note it where known, so your warranty position is clear before you commit. When we source from suppliers, we ask for it up front for exactly this reason.