diff --git a/extensions/vscode/src/views/homeView.ts b/extensions/vscode/src/views/homeView.ts
index bf92a60c9..523ed6086 100644
--- a/extensions/vscode/src/views/homeView.ts
+++ b/extensions/vscode/src/views/homeView.ts
@@ -35,6 +35,7 @@ import {
   isPreContentRecordWithConfig,
   useApi,
   AllContentRecordTypes,
+  EnvironmentConfig,
 } from "src/api";
 import { useBus } from "src/bus";
 import { EventStream } from "src/events";
@@ -944,7 +945,16 @@ export class HomeViewProvider implements WebviewViewProvider, Disposable {
     }
   }
 
-  private inputSecretName = async () => {
+  private inputSecretName = async (
+    environment: EnvironmentConfig | undefined,
+  ) => {
+    const existingKeys = new Set();
+    if (environment) {
+      for (const secret in environment) {
+        existingKeys.add(secret);
+      }
+    }
+
     return await window.showInputBox({
       title: "Add a Secret",
       prompt: "Enter the name of the secret.",
@@ -953,6 +963,9 @@ export class HomeViewProvider implements WebviewViewProvider, Disposable {
         if (value.length === 0) {
           return "Secret names cannot be empty.";
         }
+        if (existingKeys.has(value)) {
+          return "There is already an environment variable with this name. Secrets and environment variable names must be unique.";
+        }
         return;
       },
     });
@@ -971,7 +984,9 @@ export class HomeViewProvider implements WebviewViewProvider, Disposable {
       return;
     }
 
-    const name = await this.inputSecretName();
+    const name = await this.inputSecretName(
+      activeConfig.configuration.environment,
+    );
     if (name === undefined) {
       // Cancelled by the user
       return;
diff --git a/internal/config/config.go b/internal/config/config.go
index ca3733c44..ebd31de99 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -3,6 +3,7 @@ package config
 // Copyright (C) 2023 by Posit Software, PBC.
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"strings"
@@ -114,6 +115,13 @@ func (cfg *Config) AddSecret(secret string) error {
 			return nil // Secret already exists, no need to add
 		}
 	}
+	// Check if the secret name already exists in the environment
+	for e := range cfg.Environment {
+		if e == secret {
+			return errors.New("secret name already exists in environment")
+		}
+	}
+
 	cfg.Secrets = append(cfg.Secrets, secret)
 	return nil
 }
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index 0ce88dffa..92f5504f0 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -182,6 +182,14 @@ func (s *ConfigSuite) TestApplySecretActionAddNoDuplicates() {
 	s.Equal([]string{"existingSecret1", "existingSecret2"}, cfg.Secrets)
 }
 
+func (s *ConfigSuite) TestApplySecretActionAddExitingEnvVar() {
+	cfg := New()
+	cfg.Environment = map[string]string{"existingEnvVar": "value"}
+	cfg.Secrets = []string{}
+	err := cfg.AddSecret("existingEnvVar")
+	s.NotNil(err)
+}
+
 func (s *ConfigSuite) TestApplySecretActionRemove() {
 	cfg := New()
 	cfg.Secrets = []string{"secret1", "secret2"}