Reindex from ES1.3.4 to ES 6.5.3 with same _id gives error

I am trying to reindex data using _reindex API from Elastic Search 1.3.4. to Elastic Search 6.5.3. While in the Elastic Search 1.3.4 , two types(say T1, T2) have the same _id field.When I try to reindex for the T1 on to Elastic Search 6.5.3 with index T1, it runs well as _id field was not indexed before.When I try to reindex the T2 type from Elastic Search 1.3.4 on to Elastic Search 6.5.3 with index T2 , i am getting error as follows

Rejecting mapping update to [T2] as the final mapping would have more than 1 type: [T1, T2]

Please kindly provide me a solution on how to reindex the same _id on different index in Elastic Search 6.5.3.

Any solutions would be appreciated.

In Elasticsearch 6.x, each index can only have a single type, and it is this it complains about, not the _id. If you have multiple types in your Elasticsearch 1.x index, you will need to make changes to the structure when you reindex. Have a look at this blog post for some background and additional information about this change.

Thanks Christian. It was my mistake using same type in the reindex script.