HANA Joins - Record Counts - Basic Query

Hi Expert - I am new to HANA and found odd behavior , I need to know the reason for the same. Its a simple inner join between two tables.

ECC Billing Header Table

SELECT count(*)  FROM "ECC"."VBRK" -> 199407

ECC Detail Table

SELECT count(*)  FROM "ECC"."VBRP" -> 286294

When I join both the tables and ran below Query I got the count  - > 1717452

SELECT count(T1.VBELN)

     from "ECC"."VBRK" AS T1

        INNER JOIN

    "ECC"."VBRP" AS T2

        ON T1."VBELN" = T2."VBELN";

I am not able to understand the logic of count returned by the above query.

Can anyone help me in understanding this.

Thanks

R