ERA files generation can produce different files for same day

[jakubgs]

Describe the bug

It was discovered on Nimbus holesky hosts that more than one ERA file was generated for a given day:

jakubgs@geth-01.ih-eu-mda1.nimbus.holesky:~ % ls -l /docker/era/holesky-00454-*
-rw-r--r-- 1 nimbus staff 206486118 Mar  4 01:32 /docker/era/holesky-00454-a0a6ec50.era
-rw-r--r-- 1 nimbus staff 154081264 Mar 17 05:05 /docker/era/holesky-00454-f522094e.era
jakubgs@geth-01.ih-eu-mda1.nimbus.holesky:~ % ls -l /docker/era/holesky-00455-*
-rw-r--r-- 1 nimbus staff 325462253 Mar 17 05:05 /docker/era/holesky-00455-10586ca9.era
-rw-r--r-- 1 nimbus staff 153009253 Mar  4 01:44 /docker/era/holesky-00455-3ca2d3d8.era

But files appear to be "valid" based on no error when calling ncli_db verifyEra on them:h

jakubgs@geth-01.ih-eu-mda1.nimbus.holesky:~ % /data/beacon-node-holesky-stable/repo/build/ncli_db --network=holesky verifyEra --eraFile=/docker/era/holesky-00454-a0a6ec50.era
227b65c9ecb20219d21755993c0ed794d94d2e43be697d4ebefae823f04c294a
jakubgs@geth-01.ih-eu-mda1.nimbus.holesky:~ % /data/beacon-node-holesky-stable/repo/build/ncli_db --network=holesky verifyEra --eraFile=/docker/era/holesky-00454-f522094e.era
0d6fa05917c8c1bb2dffa7577e4276b2564859d44386380ae4e00bed40da9b92

Additional context

It appears on different hosts different versions of these files exist:

 > ansible nimbus.holesky -a 'ls -l /docker/era/holesky-00454-*'
geth-04.ih-eu-mda1.nimbus.holesky | CHANGED | rc=0 >>
-rw-r--r-- 1 nimbus staff 206486118 Mar  3 23:06 /docker/era/holesky-00454-a0a6ec50.era
nec-04.ih-eu-mda1.nimbus.holesky | CHANGED | rc=0 >>
-rw-r--r-- 1 nimbus staff 154081264 Mar  4 02:01 /docker/era/holesky-00454-f522094e.era
neth-04.ih-eu-mda1.nimbus.holesky | CHANGED | rc=0 >>
-rw-r--r-- 1 nimbus staff 154081264 Mar  3 21:07 /docker/era/holesky-00454-f522094e.era
geth-03.ih-eu-mda1.nimbus.holesky | CHANGED | rc=0 >>
-rw-r--r-- 1 nimbus staff 206486118 Mar  4 01:08 /docker/era/holesky-00454-a0a6ec50.era
nec-01.ih-eu-mda1.nimbus.holesky | CHANGED | rc=0 >>
-rw-r--r-- 1 nimbus staff 154081264 Mar  4 04:08 /docker/era/holesky-00454-f522094e.era
geth-01.ih-eu-mda1.nimbus.holesky | CHANGED | rc=0 >>
-rw-r--r-- 1 nimbus staff 206486118 Mar  4 01:32 /docker/era/holesky-00454-a0a6ec50.era
-rw-r--r-- 1 nimbus staff 154081264 Mar 17 05:05 /docker/era/holesky-00454-f522094e.era
...

The questions are:

• Is it normal for exportEra to produce different hashes for the same day?
• Is it normal for verifyEra to not produce an error for either of those files?
• Could this cause issues with a node trying to use this folder with ERA files?