Opening two of the same wallet (tested in v0.18.0 of bitcoin-qt 64 bit) will cause a database collision, and will crash the program.

`[marshall@likon] {21:21} [~] $ bitcoin-0.18.0/bin/bitcoin-qt `
`terminate called after throwing an instance of 'std::runtime_error'  what():  BerkeleyBatch: Can't open database 8204388-wallet.dat (duplicates fileid 8b1c090000000800e25686350000000000000000 from 1352491-wallet.dat)`
`Aborted (core dumped)`

I have been able to reproduce the issue by importing two of the same wallet (with different filenames).
if (spk_man->SignTransaction(tx, coins, sighash, input_errors)) {
                return true;
            }
            
            visited_spk_mans.insert(spk_man->GetID());
        }
    }
    return false;
}
TransactionError CWallet::FillPSBT(PartiallySignedTransaction& psbtx, bool& complete, int sighash_type, bool sign, bool bip32derivs) const
{
    LOCK(cs_wallet);
    
    for (unsigned int i = 0; i < psbtx.tx->vin.size(); ++i) {
        const CTxIn& txin = psbtx.tx->vin[i];
        PSBTInput& input = psbtx.inputs.at(i);
        if (PSBTInputSigned(input)) {
            continue;
        }
        
        if (!input.IsSane()) {
            return TransactionError::INVALID_PSBT;
        }
        
        if (!input.non_witness_utxo && input.witness_utxo.IsNull()) {
            const uint256& txhash = txin.prevout.hash;
            const auto it = mapWallet.find(txhash);