Does it hurt to use the same template for two different ecomm sites?

Do any of your clients doing this and find it ok in terms of SEO? We are considering to use the same but customized template (not those cheap templates on the market) to our two ecommerce sites in order to lower the overhead costs of running two sites, so surely, there will be footprints/marks of identicals across the two sites, however, please note that, the content of the site will NOT be the same, maybe only 30% of the content are SIMILAR but not the same, and most of the contents will be product descriptions. We will try to manual spin the descrptions.

so will it hurt in terms of on-page seo?

thanks