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).
{
    auto spk_man = GetLegacyScriptPubKeyMan();
    if (!spk_man) {
        return false;
    }
    LOCK(spk_man->cs_KeyStore);
    return spk_man->ImportScripts(scripts, timestamp);
}
bool CWallet::ImportPrivKeys(const std::map<CKeyID, CKey>& privkey_map, const int64_t timestamp)
{
    auto spk_man = GetLegacyScriptPubKeyMan();
    if (!spk_man) {
        return false;
    }
    LOCK(spk_man->cs_KeyStore);
    return spk_man->ImportPrivKeys(privkey_map, timestamp);
}
bool CWallet::ImportPubKeys(const std::vector<CKeyID>& ordered_pubkeys, const std::map<CKeyID, CPubKey>& pubkey_map, const std::map<CKeyID, std::pair<CPubKey, KeyOriginInfo>>& key_origins, const bool add_keypool, const bool internal, const int64_t timestamp)
{
    auto spk_man = GetLegacyScriptPubKeyMan();
    if (!spk_man) {
        return false;
    }
    LOCK(spk_man->cs_KeyStore);
    return spk_man->ImportPubKeys(ordered_pubkeys, pubkey_map, key_origins, add_keypool, internal, timestamp);
}
bool CWallet::ImportScriptPubKeys(const std::string& label, const std::set<CScript>& script_pub_keys, const bool have_solving_data, const bool apply_label, const int64_t timestamp)