could it be isomers? same mass different retention times ?

You can try search and match those compounds in Adam's Database, based on the RI, KI value. I think, this will help you to clarify.

You should match the mass fragmentation of your repeated compound with Adam's database.

• Normally, if the column is not properly cleaned and also there is fluctuation in any of the conditions of the instrument during analysis, it results in multiple compounds. So it's best to check based on the retention time of the same compounds which comes first, and if any of them are just a single compound coming out from there. because sometimes you have up to three compounds with the same retention time but different classes so you begin to filter which is which.

In GC-MS phytochemical analysis, include all compounds that appear at different retention times, as they may represent different isomers or forms. Present these compounds in a table with their retention times and relevant details for clarity. Including all data enhances transparency and supports the robustness of your findings in publication.