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) {
        if (spk_man_pair.second->CanProvide(script, sigdata)) {
            spk_mans.insert(spk_man_pair.second.get());
        }
    }
    return spk_mans;
}
ScriptPubKeyMan* CWallet::GetScriptPubKeyMan(const CScript& script) const
{
    SignatureData sigdata;
    for (const auto& spk_man_pair : m_spk_managers) {
        if (spk_man_pair.second->CanProvide(script, sigdata)) {
            return spk_man_pair.second.get();
        }
    }
    return nullptr;
}
ScriptPubKeyMan* CWallet::GetScriptPubKeyMan(const uint256& id) const
{
    if (m_spk_managers.count(id) > 0) {
        return m_spk_managers.at(id).get();
    }
    return nullptr;
}
std::unique_ptr<SigningProvider> CWallet::GetSolvingProvider(const CScript& script) const