diff --git a/esphome/components/api/__init__.py b/esphome/components/api/__init__.py
index 4a157f9e01..31ba63ec4d 100644
--- a/esphome/components/api/__init__.py
+++ b/esphome/components/api/__init__.py
@@ -850,7 +850,7 @@ async def api_connected_to_code(
 # user_services.cpp is only needed when user defined actions exist; the
 # frame helpers are fully #ifdef'd on the protocol defines set in to_code
 # (both are set when encryption is configured without a key).
-_filter_define_source_files = filter_source_files_from_defines(
+_define_filter = filter_source_files_from_defines(
     {
         "user_services.cpp": "USE_API_USER_DEFINED_ACTIONS",
         "api_frame_helper_noise.cpp": "USE_API_NOISE",
@@ -860,7 +860,7 @@ _filter_define_source_files = filter_source_files_from_defines(
 
 
 def FILTER_SOURCE_FILES() -> list[str]:
-    files_to_filter = _filter_define_source_files()
+    files_to_filter = _define_filter()
 
     # api_pb2_dump.cpp is only needed when HAS_PROTO_MESSAGE_DUMP is defined
     # This is a particularly large file that still needs to be opened and read
diff --git a/esphome/components/ethernet/__init__.py b/esphome/components/ethernet/__init__.py
index 84fdc9d03f..a44a609d3c 100644
--- a/esphome/components/ethernet/__init__.py
+++ b/esphome/components/ethernet/__init__.py
@@ -846,7 +846,8 @@ def _filter_source_files() -> list[str]:
         # to avoid shadowing. Native IDF builds always need the custom driver.
         if cv.Version(5, 4, 2) <= idf_version() < cv.Version(6, 0, 0):
             excluded.append("esp_eth_phy_jl1101.c")
-    return excluded
+    # The platform and define filters can both name the same file
+    return list(dict.fromkeys(excluded))
 
 
 FILTER_SOURCE_FILES = _filter_source_files