Regardless of redirects (Saw your comment), if you don't set hreflang annotations and canonicalize pages Google will likely consider them duplicates.
Via document <head>
<head>
<title>Example.com</title>
<link rel="alternate" hreflang="en-gb" href="http://en-gb.example.com/page.html" />
<link rel="alternate" hreflang="en-us" href="http://en-us.example.com/page.html" />
<link rel="alternate" hreflang="en" href="http://en.example.com/page.html" />
<link rel="alternate" hreflang="de" href="http://de.example.com/page.html" />
<link rel="alternate" hreflang="x-default" href="http://www.example.com/" />
</head>
Via headers
Link: <http://example.com/file.pdf>; rel="alternate"; hreflang="en",
<http://de-ch.example.com/file.pdf>; rel="alternate"; hreflang="de-ch",
<http://de.example.com/file.pdf>; rel="alternate"; hreflang="de"
Via sitemap.xml
<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
xmlns:xhtml="http://www.w3.org/1999/xhtml">
<url>
<loc>http://www.example.com/english/page.html</loc>
<xhtml:link
rel="alternate"
hreflang="de"
href="http://www.example.com/deutsch/page.html"/>
<xhtml:link
rel="alternate"
hreflang="de-ch"
href="http://www.example.com/schweiz-deutsch/page.html"/>
<xhtml:link
rel="alternate"
hreflang="en"
href="http://www.example.com/english/page.html"/>
</url>
...etc
This answer I wrote recently has some useful resources.