Can the LedgerJournalTrans.Voucher have duplicated values?

Hi everyone,

I am doing an integration between an external system and AX. I noticed there are duplicated Voucher numbers between different [LedgerJournalTrans].[voucher]. 

I am being told that under the same [LedgerJournalTable] scope, the included [LedgerJournalTrans] records can have the same [LedgerJournalTrans].[Voucher] values. But, different [LedgerJournalTable] records scope, the [LedgerJournalTrans].[voucher] in [LedgerJournalTable] record ONE will never have the same LedgerJournalTrans].[voucher] value as [ledgerJournalTable] record TWO.

The diagram is like 

[LedgerJournalTable] record -1-

        LedgerJournalTrans.voucher -1.1-

        LedgerJournalTrans.voucher -1.2-

        LedgerJournalTrans.voucher -1.3-

So the question is,  -1.1- and -1.3- can have the same voucher value, and -2.1- and -2.2- can have the same voucher number, But, -1.1- can never be the same voucher value with any one of -2.1- / -2.2- / -2.3-.  Is this statement correct?

We are dealing with great amounts of data, so any advice/ confirmation would be of great help!

Thank you,