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).
{
    WalletBatch batch(*database);
    return SetAddressBookWithDB(batch, address, strName, strPurpose);
}
bool CWallet::DelAddressBook(const CTxDestination& address)
{
    {
        LOCK(cs_wallet);
        
        std::string strAddress = EncodeDestination(address);
        for (const std::pair<const std::string, std::string> &item : mapAddressBook[address].destdata)
        {
            WalletBatch(*database).EraseDestData(strAddress, item.first);
        }
        mapAddressBook.erase(address);
    }
    NotifyAddressBookChanged(this, address, "", IsMine(address) != ISMINE_NO, "", CT_DELETED);
    WalletBatch(*database).ErasePurpose(EncodeDestination(address));
    return WalletBatch(*database).EraseName(EncodeDestination(address));
}
size_t CWallet::KeypoolCountExternalKeys() const