To resolve the error you're facing regarding the Many2many field in your custom model sale.order.repli, you can use the copy=True attribute when defining the field. This will create a separate table and columns for the Many2many relationship in your custom model. Here's an updated version of your code:

from odoo import api, fields, models

class SaleOrderRepli(models.Model):
_inherit = "sale.order"
_name = "sale.order.repli"

transaction_ids = fields.Many2many('sale.transaction', 'sale_order_repli_transaction_rel', 'order_id', 'transaction_id', copy=True)
In the above code, we added the copy=True attribute to the transaction_ids field definition. This will ensure that a separate table and columns are created for the Many2many relationship in your sale.order.repli model, avoiding conflicts with the same field in the original sale.order model.

After making this change, you should be able to create and use the sale.order.repli model independently without encountering the "TypeError: Many2many fields use the same table and columns" error.

I had the same issue when inheriting res.partner it got fixed somehow my uninstall my custom module and rerun my code somehow it worked somehow. I dont know exact reason how it got fixed