do not concatinate params. fixes #452, fixes #453.

lib/sinatra/base.rb

@@ -829,7 +829,7 @@ module Sinatra
 
       if values.any?
         original, @params = params, params.merge('splat' => [], 'captures' => values)
-        keys.zip(values) { |k,v| (@params[k] ||= '') << v if v }
+        keys.zip(values) { |k,v| Array === @params[k] ? @params[k] << v : @params[k] = v if v }
       end
 
       catch(:pass) do

test/routing_test.rb

@@ -236,6 +236,12 @@ class RoutingTest < Test::Unit::TestCase
     assert_equal "format=", body
   end
 
+  it 'does not concatinate params with the same name' do
+    mock_app { get('/:foo') { params[:foo] } }
+    get '/a?foo=b'
+    assert_body 'a'
+  end
+
   it "supports single splat params like /*" do
     mock_app {
       get '/*' do