Just posting that here in case you're awake when I'm not!
I have two identical boxes on testnet right now (not mining).
Edit: Woops I'm stupid editing my message.
No errors yet on testnet but this is what one of the node got when it was on mainnet and it was mining.
2017-11-16 01:53:00 ProcessNewBlock : ACCEPTED
2017-11-16 02:01:14 CheckProofOfWork(1.0): BlockHash 333e1c9e6fc52027012f734b2b701a3325591759ec6f29686879faae98a4b585, ProdChain TRUE, SSLVersion OpenSSL 1.0.1t 3 May 2016, BlockTime 1510797674.000000, PrevBlockTime 1510797171.000000, BibleHash 0000000000072c18e0c42605b5431bd2e2343ced7942038c6a39f76ffa077225, TargetHash 000000000007e281000000000000000000000000000000000000000000000000, Forensics exec biblehash 333e1c9e6fc52027012f734b2b701a3325591759ec6f29686879faae98a4b585 1510797674 1510797171 16911
2017-11-16 02:01:14 ERROR: CheckProofOfWork(1): BibleHash does not meet POW level, prevheight 16911.000000 pindexPrev f3479b24cae1e5b5fb10572b0eac0ea45492f7f4e32e88029ce72eb6cd48b1bb
2017-11-16 02:01:14 ERROR: CheckBlockHeader(): proof of work failed
2017-11-16 02:01:14 ERROR: ProcessNewBlock: CheckBlock FAILED
2017-11-16 02:01:14 Misbehaving: 217.182.73.71:40000 (0 -> 5)
2017-11-16 02:01:14 UpdateTip: new best=333e1c9e6fc52027012f734b2b701a3325591759ec6f29686879faae98a4b585 height=16912 log2_work=57.78389 tx=28553 date=2017-11-16 02:01:14 progress=1.000000 cache=0.0MiB(7tx)
--
2017-11-16 03:03:15 ProcessNewBlock : ACCEPTED
2017-11-16 03:03:39 CheckProofOfWork(1.0): BlockHash 5468ae8523dbe8fc9d895343f0deb9f27a7d74763eb4d0cf8e71a419c77b5395, ProdChain TRUE, SSLVersion OpenSSL 1.0.1t 3 May 2016, BlockTime 1510801402.000000, PrevBlockTime 1510801390.000000, BibleHash 00000000000677ab6388f8cd607de8c458d9083599fef6192c63b517bf3eb730, TargetHash 00000000000a858a000000000000000000000000000000000000000000000000, Forensics exec biblehash 5468ae8523dbe8fc9d895343f0deb9f27a7d74763eb4d0cf8e71a419c77b5395 1510801402 1510801390 16917
2017-11-16 03:03:39 ERROR: CheckProofOfWork(1): BibleHash does not meet POW level, prevheight 16917.000000 pindexPrev 89d18d6ae6043337ed9b650244e7e4fac4004aa7d61e40e892d51ea9dd9e7955
2017-11-16 03:03:39 ERROR: CheckBlockHeader(): proof of work failed
2017-11-16 03:03:39 ERROR: ProcessNewBlock: CheckBlock FAILED
2017-11-16 03:03:39 Misbehaving: 208.113.166.223:40000 (0 -> 5)
2017-11-16 03:03:39 UpdateTip: new best=5468ae8523dbe8fc9d895343f0deb9f27a7d74763eb4d0cf8e71a419c77b5395 height=16918 log2_work=57.785222 tx=28561 date=2017-11-16 03:03:22 progress=0.999999 cache=0.0MiB(16tx)
--
2017-11-16 03:44:09 ProcessNewBlock : ACCEPTED
2017-11-16 03:57:38 CheckProofOfWork(1.0): BlockHash 6c8efa4788a6aa5e42d2d7b5f54fe24e1f9fb4483fa707fcfe4b4c8ec0bbdf57, ProdChain TRUE, SSLVersion OpenSSL 1.0.1t 3 May 2016, BlockTime 1510804572.000000, PrevBlockTime 1510803844.000000, BibleHash 0000000000007a70102622f79b71810b12687066d52a06d53ff74f9a59389587, TargetHash 00000000000947eb000000000000000000000000000000000000000000000000, Forensics exec biblehash 6c8efa4788a6aa5e42d2d7b5f54fe24e1f9fb4483fa707fcfe4b4c8ec0bbdf57 1510804572 1510803844 16922
2017-11-16 03:57:38 ERROR: CheckProofOfWork(1): BibleHash does not meet POW level, prevheight 16922.000000 pindexPrev c49314cb92548b7722cccbb773922c48f3eb4fe9fe6a0e3c95a129312f9161c8
2017-11-16 03:57:38 ERROR: CheckBlockHeader(): proof of work failed
2017-11-16 03:57:38 Misbehaving: 208.113.166.223:40000 (5 -> 10)
2017-11-16 03:57:38 ERROR: invalid header received 6c8efa4788a6aa5e42d2d7b5f54fe24e1f9fb4483fa707fcfe4b4c8ec0bbdf57
2017-11-16 03:57:38 UpdateTip: new best=6c8efa4788a6aa5e42d2d7b5f54fe24e1f9fb4483fa707fcfe4b4c8ec0bbdf57 height=16923 log2_work=57.786245 tx=28570 date=2017-11-16 03:56:12 progress=0.999997 cache=0.0MiB(38tx)