If a second seal fails in the same pump, I would not start by ordering a third. The failed seal is evidence. So is the pump it came out of.
Start with the timeline. Did both failures happen on startup, after the same number of running hours, after cleaning, or when the process changed? Keep each removed seal and mark its position and running direction. Photograph the faces, the sleeve, the gland and the damaged elastomer before cleaning them.
Then check what the seal was asked to do. Record the actual fluid, concentration, pressure, temperature, speed and any dry running or solids. Compare those conditions with the seal specification. A seal selected for yesterday's duty may be wrong for today's process.
Do not stop at the seal. Check bearings, shaft movement, alignment, the sleeve and the seal chamber. Look at the flush or barrier supply while the pump is running. A wide or eccentric wear track can point to shaft movement or alignment. Damaged faces can point to heat, poor lubrication or contamination. None of those marks proves a cause on its own.
The cost is not the price of the replacement seal. Write down the hours stopped, lost production, labour, cleaning, wasted product and any urgent parts or outside work for each event. That gives you a cost per failure. It also tells you whether a better material, a pump repair or a change to the operating conditions is the sensible first move.
Send the two failed parts, photos and operating record for review before fitting another identical seal. If the pump needs work, a more expensive seal will not fix it.
Related: Seal Troubleshooting Guide, How do I measure an unknown mechanical seal for replacement? and What should I send to identify an unmarked or obsolete seal?.