Identical tables in schemas, data inserted into the wrong schema

We have tables into schemas which are identical. Occasionally we find that records were inserted or updated in the wrong schema. What makes us think it's an oracle issue, is that the transaction is in PL/SQL procedure, and there are no grants to insert or even select between schemas. Can't rule out an application issue completely yet, but app never connects to 2 schemas at the same time, and what kind of points that a transaction occurs within pl/sql is that the records that are inserted in the wrong schema and the right schema as part of the same transaction have the same timestamp.

Before we start digging through redo logs with logminer, I wanted to know if there are any known bugs on the issue. This is not consistent or reproducible issue at this point. This would have to be a pretty big bug.

version is 10g std
Oracle Database 10g Release 10.2.0.2.0 - 64bit Production PL/SQL Release 10.2.0.2.0 - Production
CORE 10.2.0.2.0 Production
TNS for Linux: Version 10.2.0.2.0 - Production NLSRTL Version 10.2.0.2.0 - Production

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We run Oracle 9iR2,10gR1/2 on RH4/RH3 and Solaris 10 (Sparc) remove NSPAM to email Received on Mon Apr 16 2007 - 12:52:21 CDT