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 (!locked_chain.checkFinalTx(*tx)) return false;
    int nDepth = GetDepthInMainChain();
    if (nDepth >= 1) return true;
    if (nDepth < 0) return false;
    
    if (!pwallet->m_spend_zero_conf_change || !IsFromMe(ISMINE_ALL)) return false;
    
    if (!InMempool()) return false;
    
    for (const CTxIn& txin : tx->vin)
    {
        
        const CWalletTx* parent = pwallet->GetWalletTx(txin.prevout.hash);
        if (parent == nullptr) return false;
        const CTxOut& parentOut = parent->tx->vout[txin.prevout.n];
        
        if (pwallet->IsMine(parentOut) != ISMINE_SPENDABLE) return false;
        
        if (trusted_parents.count(parent->GetHash())) continue;
        
        if (!parent->IsTrusted(locked_chain, trusted_parents)) return false;
        trusted_parents.insert(parent->GetHash());
    }
    return true;
}
bool CWalletTx::IsEquivalentTo(const CWalletTx& _tx) const