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).
{
    std::set<ScriptPubKeyMan*> spk_mans;
    for (const auto& spk_man_pair : m_spk_managers) {
        spk_mans.insert(spk_man_pair.second.get());
    }
    return spk_mans;
}
ScriptPubKeyMan* CWallet::GetScriptPubKeyMan(const OutputType& type, bool internal) const
{
    const std::map<OutputType, ScriptPubKeyMan*>& spk_managers = internal ? m_internal_spk_managers : m_external_spk_managers;
    std::map<OutputType, ScriptPubKeyMan*>::const_iterator it = spk_managers.find(type);
    if (it == spk_managers.end()) {
        WalletLogPrintf("%s scriptPubKey Manager for output type %d does not exist\n", internal ? "Internal" : "External", static_cast<int>(type));
        return nullptr;
    }
    return it->second;
}
std::set<ScriptPubKeyMan*> CWallet::GetScriptPubKeyMans(const CScript& script, SignatureData& sigdata) const